To answer your question... No Talk is not the same as Voice.
Google talk can be used to chat or video conference by phone or computer. Google Voice is more for phone calls and texts between phone / phone or computer.
Google has A LOT of tidying up to do here because it is confusing. Google Talk & Google+ Messenger should be merged. Why have both? On the computer you can Google Talk with someone from within Gmail. Or you can chat/video from within Google+ 's website. Then you can text people within Google Voice. It really is all too confusing. They need to start merging all these services and create some greater lines of clarity.