Mac Noob trying to learn a few things...

New to Mac bought a used MacBook Pro only to find I'm locked out aftyer going online....4 pin EFI Using Teensy 3.1 but completely uncertain as to how to use it.
What is the difference IEF and icloud lock and how to tell?

If EFI locked, it appears a lock and a place when you can enter the password (no character limitation), if iCloud locked, it appears the apple logo and 4 or 6 spaces (numerical only).

Although there's no character limitation, usually the EFI password is 4 characters long if its iCloud locked. Maybe someone who know better can help you more. But you can diferenciate those two screens by the image that appears.

When it boots it shows the iCloud 4 pin lock but it's my understanding that in order to hack into it you have to be in the EFI screen in order for Teensy to do it's job or have I misunderstood.Possibly both locks use the same 4 pin #?