The first version is a SINUSOIDAL projection, while the second is a MERCATOR projection.
You can find the descriptions of these and other projections here:
http://pubs.er.usgs.gov/usgspubs/pp/pp1395 (downloadable PDF file)
Of course, if you hate dry documents, a quick writeup on the various common types of projections can be found here:
Thank you sir. :)
I'm manually keywording 10,000+ pics and I have over 500 map pics. This will help me out.
(I'll be reading the pdf after I get back from lunch.)
egad! 394 pages... I'll be skimming through it when I have time. hehe