Exp given per mob
 

So I'm sitting at level 34 and wondering do all blue con mobs give same exp or will a higher level blue con give more (assuming same zem).

Higher level blues give more than lower level blues. The amount of exp given is a function of the mob level, not necessarily the con color (exception - low greens give zero exp).

If you dig around the wiki, you can find discussions about how the exp given is proportional to the (mob level)^2, (i.e. squared)

Higher level (not neccesarily higher difficulty) mobs give more EXP.

There is a range of levels within blue, there was a light blue color that was unclassically present in p99 but has since been removed, so now you gotta look at the EXP bar to know what mobs are light blue.

Some static spawns are always higher level than other static spawns. Some come back at random levels. ETC.

Man I loved scoping out the higher con skeletons at ruins thinking "I wonder if I could take that fucker"

then I would kite the guy for like 30 percent of his HP and then melee him and within 2 seconds I'm at 50% and running full coward style haha