I know both extremely well and have used them for a long time now. I work as a 3D artist for a living. You should buy teaching books online from Chapters/Indigo...something like
Mastering Autodesk Maya 2001 by Eric Keller can teach you a lot but if you want to learn the basics..... I'd go with something like Learning Autodesk Maya 2008 Foundation (Official Autodesk Training Guide)
You can find tons of online tutorials but usually they cannot explain how to do it well -as their way makes most sense to them and not the general public. To be blunt- it really depends on what you already know and what you want/need to know.