You also get 4GB GDDR5 memory clocked at the same 7008MHz but what's different is that the base and boost clockspeeds of the mobile version are quite a bit higher. While the desktop GTX 1050 Ti has a 1290MHz core and 1392MHz Boost, the mobile version is said to have a 1490MHz core frequency and 1624MHz Boost!
VideoCardz came across leaked benchmarks and notes the mobile GeForce GTX 1050 Ti will end up faster than the old GeForce GTX 970M. In synthetic benchmarks like the 3DMark Cloud Gate and Fire Strike, as well as the Unigine Heaven 4 test, the GTX 1050 Ti Mobile is about 7-10 percent faster than the GTX 970M.
Here's a video from LaptopMedia showing the performance of the mobile GTX 1050 Ti in Doom at Full HD resolution with Ultra settings.