How are Different Mages 'Handled'?

i think you got most of it. i/l basically mob kill the entire time while f/p use poison to train. this leads to some pretty drastic differences though. i/l mages, if they choose to do so, can party with other people in 3rd job to split maps etc. f/p mages, with their poisoning, tend to take over whole maps. there is a pretty significant difference in cost and speed as well. fp mages, if used well, can train extremely quickly with low cost. however, if you bump into half of the monsters you try to kill, you can go broke very quickly. i/l mages tend to have more stable costs to training. in 4th job, the differences disappear a bit, but i/l mages still have the ability to freeze monsters when training, which gives them a somewhat reduced cost.

not sure what else. the main thing is that the training styles are different up to 4th job, so one class may be more suitable to you than the other.