Both are the same colleges with same type of faculty and same placement, JIIT-128 is justa extended version of JIIT-62. Sector 62 is located at a very good place and in very close to the city but 128 campus is around 18KM away from the main campus(JIIT-62) and situated in Noida expressway.
You should know that the sector 128 don't have a hostel, they are living in the hostel of JIIT-62 and also JIIT-128 students come to the main campus i.e. JIIT-62 for the placements. But still everything is same in both the campuses and if you are getting both then I will suggest you to go with the JIIT-62.
Good Luck :)