# Magnetic field strength vs flux density

What's the actual difference?

I've been told that they're the same thing; however, I seem to remember reading somewhere that where are different types of measures for field strength, denoted by the letters B and I think 2 others.

It's the "old" way of speaking. If you are learning E&M now, most modern books will use SI units and the $\mathbf E, \mathbf B, \mathbf D, \mathbf H$ fields.
Nowadays, we call $\mathbf B$ the magnetic field and $\mathbf H$ just the "H field". In the older books, they call $\mathbf H$ the magnetic field, and $\mathbf B$ the magnetic flux density or something of that sort.