WAP: WAP stands for Wireless Application Protocol.
As the definition states, WAP is in fact a protocol or standard which has many different facets to it.
The most common use of the protocol is in the production of "WAP sites" or mobile websites.
GPRS: a mobile network technology which allows data to be transferred (as opposed to voice for example). Essentially, it is how a phone connects to the internet. It is a very low cost alternative as the field worker is only billed for the data transferred (which is minimal for a survey).
Newer technologies which provide faster transfer rates are becoming more common such as EDGE and 3G (used if available).