I've read some of the threads about process vs. enlarging lens, and understand that I should NOT get a process lenses.
But on the used market, how do I tell what is a process lens from an enlarging lens?

I got more confused when I read a post that said that the Rodenstock Rodagon was available in BOTH process and enlarging lens. So that post told me that I could not even depend on the name Rodagon to be an enlarging lens, I could accidentally purchase a Rodagon process lens thinking it was a Rodagon enlarging lens.
Are there any visual clues on the lenses of the different brands to indicate enlarging vs. process?

For enlarging, I am limited to printing 16x20 or slightly larger. So no large magnification requirement. 4x5 will be max 5.5x enlargement and 6x6 will be max 11.5x enlargement.
I am looking first for a 135 (4x5) and next for a 105 (6x9) lens.
And for now, because of lack of budget, I will not be looking at APO lenses. Unless someone offers me a godfather deal.

This pix is an example of what I found on eBay.
The left lens looks like an old lens that I used to use in high school.
The middle lens I have never seen before. Is it a process lens?
The right lens looks like the current enlarging lens.