Surface Pro - Screen size 12.3", battery - upto 9 hours (declared), CPU starts from m3 to i7, need to buy keyboard
Surface Book - Screen size 13.5", battery - up to 12 hours (Performance base - up to 16), discrete GPU
Surface Laptop - Screen Size 13.5", battery up to 14.5 hours
The surface book is more suited for heavy uses or gaming, although the Surface Pro i7 version can also do "heavy lifting" but cooling in the Book is better.