From the Out of the Park Developments website:
OOTP Developments proudly presents the new version of Title Bout Championship Boxing, TB 2.5! Discount offer for owners of TB1 and TB2!
TB 2.5 is a milestone on the way to the role playing version of the game and will replace TB2. It includes a lot of new, powerful features, a completely redesigned database and a new graphics engine.
TB 2.5 comes with more than 6600 updated fighter records and is linked to our new online fighter database, which is constantly being updated by a team of dedicated volunteers. This way you'll receive changes and additions on your computer as soon as they have been added to the online database!