They can have multiple senses. You can distinguish to some extent by their accompanying phrases, but the tricky part is knowing when you have a phrasal verb rather than a verb followed by a preposition.
go on has five separate senses noted in Princeton WordNet:
S: (v) continue, go on, proceed, go along, keep (continue a certain
state, condition, or activity) "Keep on working!"; "We continued to
work into the night"; "Keep smiling"; "We went on working until well
past midnight"
S: (v) happen, hap, go on, pass off, occur, pass, fall
out, come about, take place (come to pass) "What is happening?"; "The
meeting took place off without an incidence"; "Nothing occurred that
seemed important"
S: (v) advance, progress, pass on, move on, march
on, go on (move forward, also in the metaphorical sense) "Time marches
on"
S: (v) continue, go on, carry on, proceed (continue talking) "'I
know it's hard', he continued, 'but there is no choice'"; "carry
on--pretend we are not in the room"
S: (v) go on, come up, come on
(start running, functioning, or operating) "the lights went on"; "the
computer came up"
The first sense takes a complement verb phrase in its present participle form. The remaining senses second, third and fourth senses are intransitive. The example that another answer gives ("go on to bigger and better things") is debatable whether it's better analyzed as a phrasal verb ("go on") + a prepositional phrase ("to bigger...") or if it's a case of preposition doubling akin to ("climb up to the fourth floor").
go ahead as a phrasal verb has only one sense listed on WordNet:
S: (v) go ahead, plow ahead (proceed (with a plan of action)) "He went
ahead with the project"
One sense that I can think of that's not phrasal verb use is would be like "you go ahead, we'll catch up", where "ahead" functions similar to "home" in "go home".
The definitions for each of these words intersect at provide money, but each word carries unique connotations that shade the context of that provision . The discrete connotations of each word can be infered from their etymologies, and their current usage.
Defray has connotations rooted in fixing a broken situation:
1540s, from Middle French defraier (15c.),
perhaps from de- "out" (see de-) + fraier "spend,"
from Old French frais "costs, damages caused by breakage,"
from Latin fractum, neuter past participle of frangere "to break" (see
fraction).
Alternative etymology traces second element to Old High German fridu
"peace," via Vulgar Latin *fredum "fine, cost."
Etymonline.com
Whichever etymology is accepted, the connotation of defray implies that a separate party engages in an activity and experiences costs or expenses that the defraying party agrees to share, often after the fact, but almost always in an ancillary relationship:
Oil money also paid for a huge Soviet military buildup that,
incredibly, enabled the country to reach rough parity with the United
States. And it helped defray the costs of the war in Afghanistan,
launched in the late 1970s. [Armageddon Averted: Soviet Collapse,
1970-2000, Stephen Kotkin, page 16. Emphasis mine.]
Fund has connotations rooted in laying a foundation:
(v)
1776, "convert (a debt) into capital or stock represented by
interest-bearing bonds,"
from fund (n.)...
[1670s, "a bottom, the bottom; foundation, groundwork,"
from French fond "a bottom, floor, ground" (12c.), also "a merchant's
basic stock or capital,"
from Latin fundus "bottom, foundation, piece of land,"
from PIE root *bhudh- "bottom, base"
(cognates: Sanskrit budhnah, Greek pythmen "foundation, bottom," Old
English botm "lowest part;" see bottom (n.)). Meaning "stock of money
or wealth available for some purpose" is from 1690s; sense of "store
of anything to be drawn upon" is from 1704. Funds "money at one's
disposal" is from 1728.]
...Meaning "supply (someone or something) with money, to finance" is
from 1900.
Etymonline.com
The connotation of the verb fund implies that the money is a fundamental contingency of the activity, and often that the funding party is committed at a fundamental level:
This chapter is for the way Mr. and Ms. America invest in order to pay
the bills, get out of debt, put their kids through college, and fund
their retirement. [Living Rich for Less, Ellie Kay, page 83. Emphasis mine.]
The second section describes major sources of revenues for each level
of government to fund their services, including revenues that are
raised by a government itself as well as intergovernmental transfers.
[Handbook of Governmental Accounting, Frederic Bogui ed., Page
130. Emphasis mine.]
In exchange for a senior claim on specific assets of the hedge fund,
the prime broker will partially fund the manager's purchase of
securities. [Managing Hedge Fund Risk and Financing, David P.
Belmont. Emphasis mine.]
Sponsor has connotations rooted in a solemn guarantee:
1884, "to favor or support,"
from sponsor (n.)...
[1650s, from Late Latin sponsor "sponsor in baptism," in Latin "a
surety, guarantee, bondsman,"
from sponsus, past participle of spondere "give assurance, promise
solemnly" (see spondee).
Sense of "person who pays for a radio (or, after 1947, TV) program" is
first recorded 1931.]
...Commercial broadcasting sense is from 1931.
Etymonline.com
The connotation of sponsor implies that the sponsoring party is committing superior resources--often but not always money--to support the expensive or risky activity of another less endowed party:
This program created a legal channel and enabled emigres to sponsor
their families in Cuba. [Guantánamo: A Working-Class History Between
Empire and Revolution, Jana Lipman, page 200. Emphasis mine.]
We were of the impression that, at this point, the district would give
us a go ahead since they already agreed to sponsor our secondary
program. [Keeping the Promise: One Charter School's
Experience, Samuel Yigzaw.]
Though the words share a common definition, the various shades of meaning in each word makes it more suitable in some contexts and less suitable in other contexts. From the corpus:
- "Money" will most likely fund a program, and less likely sponsor a program, but will never defray a
program.
- "Money" will most likely sponsor a team, and less likely fund a team, but never defray a team.
- "Money" will most likely defray costs, and less likely fund costs, but will rarely sponsor costs.
Best Answer
Starting with A includes only words that start with the letter A.
Starting from A gives you all the words that start with A and all the words that start with the letters after A.
Your wording makes the difference less clear. For example I think the following is clearer.
When there is no known ordering, they mean the same thing so with/from can be used interchangeably in the following example.
So I'm of the opinion they can be used interchangeably if there is no order to what is being started with/from, though with is more correct in my opinion. When order matters, starting from includes all items starting with and coming after.