There is a difference. It is now 2015 ...
Year before last designates a specific year. If you say I finished school the year before last we understand that you finished school during the year which preceded last year: sometime in 2013.
Before last year designates an indefinite timespan which ended at the beginning of last year. If you say I finished school before last year we understand that you finished school at some unspecified time before last year. It might have been 2013, it might have been 2012, it might have been 1990 or 1980 or 1970 or 1960 ...
By the way, in US English you need not say the year before last—this is fine:
I finished school year before last.
SHORT VERSION:
Only if you change the first statement to
I have experience in something
does it have the same meaning as the second statement.
LONG VERSION:
Make sure you understand the difference between (2) and (3) in the treatment of the noun here:
2.
a. Active participation in events or activities, leading to the accumulation of knowledge or skill . . .
b. The knowledge or skill so derived.
3.
a. An event or a series of events participated in or lived through.
as well as the difference between the adjective experienced:
- Having had experience in an activity or in life in general: a highly experienced traveler.
- Skilled or knowledgeable as the result of active participation or practice: consulted an experienced investment counselor.
and the past tense of the verb, experience(d) (below the noun entries linked above):
To participate in personally; undergo; experience a great adventure; experienced loneliness
Now to address your examples:
"I've had an experience in something"
is unusual phrasing. It looks like an awkward cross between "I had an experience" (noun, 3) and "I have experience with _____" (noun, 2).
Normally, "an experience" specifies one event or occasion, as in definition 3a above. This is singular and therefore distinct from the idea of ongoing experience.
But experience "in something" suggests practical exposure, as in definition 2a.
"I'm experienced in something"
This is much clearer than your previous phrase, because the adjective experienced only corresponds to Definition 2 of the noun; there is no equivalent adjective "experienced" that corresponds to the noun's Definition 3.
Best Answer
"Travel around the world" is often used in a fairly literal sense of proceeding more-or-less entirely in a single direction in order to proceed around the globe in a giant circle.
"Travel the world" is used to speak going to a relatively large number of varied international destinations. Someone who has made seven trips to Paris would not be considered to have "travelled the world", but someone who has made one trip each to Paris, Rome, Moscow, Perth, Cairo, Singapore, and Mumbai would have a much better claim to it.