From Wikipedia
Human societies are characterized by patterns of relationships between individuals sharing a distinctive culture and institutions. Without an article, the term refers either to the entirety of humanity or a contextually specific subset of people.
I would restate one part of the original question as
'"society" (without "the") refers to human society in general'
and, the example should read
"socialization is the process of learning to live in society"
The phrase "the society" is used in areas of study such as anthropology, political science and sociology when referring to specific groups.
Again from the Wikipedia article, discussing a particular group
This nobility organized warriors to protect the society from invasion.
In this case, "the society" is used to limit the scope to the group under discussion, and not all of humanity.
Edited to respond to OP's edit of original question
In "Soldiers protect society" the lack of an article preceding "society" makes it a statement about human society in general. As such it can stand alone without other context.
"Soldiers protect the society" seems taken out of context. It begs the question which society?
(Note: The following example statements are not meant to be historically accurate.)
In general, soldiers protect (human) society.
In ancient Rome, soldiers called centurions protected the (Roman) society.
In ancient Japan, soldiers called samurai protected the (Japanese) society.
Are you defining "geography" to encompass only natural phenomena such as the shape and location of landmasses and their features? Or are you including demographic and sociological factors like population density, literacy rate, and so forth?
If the former, consider something like geophysics (which would be better used in adjectival form, e.g. "geophysical factors") or physical topology.
If the latter, that's probably too broad a category to be considered as a single unit, although in a pinch you could resort to something unwieldy like "geographic and demographic factors."
In either case, "environment" should suffice as a contrasting category once you've differentiated it from the other one.
Best Answer
Not much.
Both mean pretty much the same thing, but start is felt to be slightly less formal than begin (possibly a result of the extra syllable in begin).
Both words occur in most idioms that feature one or the other (these sentences are all grammatical and also synonymous):
But the second sentence in the following is ungrammatical, so there's some difference, at least in the verbal usages: