The Contender is T/C's original break-action switch-barrel receiver. The Encore is a later "magnum" version of the concept (with slightly different mechanics). The G2 Contender is a revamp of the Contender, using more Encore-like mechanics, but still in the more compact "non-magnum" frame. Contender and Encore barrels don't interchange, but Contender and G2 both use the same barrels.
I'll echo my standard opinion on the subject: I'd handle the Encore and Contender side-by-side before deciding between the two. I personally find the Contender light and graceful, the Encore as heavy and clunky as most bolt-actions.
The Contender cannot chamber as large of a variety of cartridges as the Encore, admittedly a shortcoming. However, seeing as how the Contender chambers .22LR, .223, 30-30, and 45-70, and many many similar cartridges, many would argue that a Contender covers all the bases. For handloaders, the field is even wider, with wildcats like the .375 JDJ satisfactory for elephants and Cape buffalo.
If you fire factory ammo only, and want to be able to fire rounds like 25-06, .300 WinMag or .458 WinMag, then the Encore will accept those. For a overview of the variety of cartridges availabe in each frame,
www.bullberry.com gives a pretty good list.
So, if the ability to fire a wider variety of cartridges is worth a notable tradeoff in compactness and agility, go for the Encore. If you're willing to be a bit more creative with cartridges, and value a light, fast-handling pistol or carbine, go Contender. Just my personal convictions... -MV