Say you are seeing a video file which can be broken into 2 tasks. 1. Loading the part of the whole file into the memory and 2. Display it.
Now when the loading overlaps with the I/O its buffering.
Spooling is Say you are trying to print a document but your PC can print the job much faster than the actual hardware can complete the job and so your PC cannot wait for the job to complete and so it spools the complete job and return back to some other work and that may be saving the file or other thing.