What is a speedlight vs a flash?
A speedlight (aka speedlite) is a small external flash unit meant to attach to a small camera like a DSLR. You would not refer to a studio flash/strobe system as a speedlight.
One last photoshop term explained for your edification.
Leading. Pronounced "led ing" not "leed ing". Leading refers to the space between lines of type. In the early days of printing, printers used type characters made of lead. When they needed more space between lines of type the would add bars of lead to separate the lines. Hence "leading".