The same =and= different. Mongoose is publishing T5 Lite (basically), then tying licensed worlds to it. Far Future is publishing T5, which is touted as a "superset" of the Mongoose rules. Everything's compatible, so if you want to use the full T5 rules in your Mongoose-published Starship Troopers game, you can do that.

And Mongoose is publishing a Strontium Dog rulebook. Yay for cheesy early '80s indy Brit comics!

Here's the announcement at Mongoose's site.