Source:
http://forum.ppcgeeks.com/showthread.php?t=96250
Q: What is Difference Between HTC Sense 2.1 & HTC Sense 2.5?
A: Here are the Known Differences
-2.5 Has a Widget Themed Home Screen (For Shortcuts)
-2.5 Has Social Networking (Twitter, Facebook, Footprint, YouTube & Facebook Uploader built into HTC Album
-2.5 Has Deep Roots in the ROM itself. Meaning it tries to control many of the phones functions through Manila. For Example, the settings tab in manila are much more expansive to many features that control phone. text messaging is built into manila even though MMS does not work. things like that show that HTC is trying to TAKE OVER the OS, so to speak....
-2.5 is Designed for 1GHz Processor and might be too much for TP2
UPDATE* Manila 2.5 IS a bit much for TP2. i have tried ROM's with Manila 2.1 & Manila 2.5
Manila 2.1 is Faster, BUT Manila 2.5 is not THAT bad. i have used manila 2.5 since i could flash my TP2 and will probably go back an forth. Just love the features of Manila 2.5