Difference between 720p and 1080p projectors?

Thanks for all the info guys; just when I think I'm understanding more about this hobby, I'm humbled again. If later this year, I was to upgrade to a 1080p projector for Blu-ray DVDs, what projectors would you recommend for under $2,000?

I upgraded from an Optoma H77 (which I loved) to a Epson
7500ub last year. Also as part of this upgrade, I went
from a Pioneer Elite SD dvd player to a Pioneer elite blu-ray player. The difference is honestly night and day. The Epson ($3000) is so superior to the H77 ($5750) four years ago that it really is worth getting into 1080p as soon as you can afford it. With 1080p you will never go to a movie theater again.

you can buy a 720p projector to save some bucks, and then consider upgrading when 1080p projectors become affordable.

The Optoma HD20 is $999, and is an amazingly good 1080p DLP projector for the price. Also very bright--I can use it in a room with quite a bit of light. The 1080p projectors tend to best the 720p in a variety of ways, not just resolution. But even for lower resolution sources you will get a smoother picture. Blu-ray looks absolutely as good or better than any picture I have ever seen in a theater.

A 1080p pj will certainly look better than a 720p pj when it comes to br. Hdtv is another story. It may or may not look better depending on broadcast and your lighting conditions remembering that with ambient light you need more lumen output. I have a new Epson 8100 and could not be happier. It's not my dream jvc but it's kickbutt for 1.5k