I want to know the difference between MLX90614ESF-BAA-000-TU and MLX90614ESF-BAA-000-SP.
The parts are actually the exact same. The SP or TU suffix from Melexis is calling out the supplier packaging. The SP is going to be a bulk package and the TU would be a tube package from the factory.
Here is the part breakdown from the datasheet. While it does not say in this data sheet what the packaging stands for, I can tell you from experience it is calling out bulk vs tube. Some Melexis products also use an RE suffix which would be Tape and Reel.