what is the difference? i.e which one am i on?
internet gprs or wap gprs?
Wap gprs is yes limited. You can only visit only wap sites and maybe download some files and de some html(depending on the phone and the operator). Internet gprs gives you full access to internet. Eg you can receive and send e-mails talk to irc, stream audio or video etc etc...
how can u tell which one u are on?
Only by asking from your operator, (and get answer: "we dont know" 😃 )
The simple way. Try to send or receive a e-mail. If you can't you have wap. If you can you have internet. The had way. Check your access point you are using and ask your operator. Also notice that usually internet gprs is only offered on customers on contract (not prepaid) and most of the time with an extra monthly fee... So it is more likely you have wap gprs unless you pay some extra fee every month for gprs or your operator is giving it free(very hard to find)...