Multifocal is a broader term that includes all lenses with multiple focal points, while progressive is a specific type of multifocal lens that provides a gradual change in focal power across the lens. This gradual change makes for a more seamless transition between distances compared to older multifocal designs like bifocals and trifocals.
Therefore, you can use the terms "multifocal" and "progressive" interchangeably when referring to glasses that correct vision at multiple distances.
However, some people might use "multifocal" to refer to any lens with more than one focal point, including bifocals and trifocals, while "progressive" is reserved for the newer gradual-transition design.
Ultimately, it's important to understand the context and the speaker's intent to determine the exact meaning of "multifocal" or "progressive".