which is better

- separating workouts according to: push muscles / pull muscles

- or seperating workouts according to: place of muscles on body (chest and biceps one day, legs the other day...etc)

I think it's highly debatable which one is "better". Different approaches work for different people. Personally I used to work by muscle group (chest, bicep, back etc) but about 3 weeks ago I switched to push/pull/legs, and I probably prefer the new technique. I find I'm able to work harder and I feel more exhausted at the end of workouts now.

Only real answer is to try both for about 6 -8 weeks each and see which one you prefer, or better still keep switching between the two - variation is the name of the game in weight training, it keeps you interested and keeps your muscles guessing. :)