What is the difference between BPDU Guard and Filter?
Yes they are two completely different things.
BPDU Guard is designed to protect your network from unauthorised switches, or from loops. What it says is "If you see a BPDU on this port, then shut the port down." It is recommended to have BPDU Guard on all user-facing ports.
BPDU filter switches off the BPDUs, and as such is very dangerous unless you are absolutely sure you need it. What it does is to stop sending or receiving BPDUs on this port. BDPUs are what protects your network against loops, so you can see that blocking them is to take a great risk. Do not use bpdufilter unless you have a specific very valid reason for doing so.