"Is there a difference between "collecting" something (like Riverboats) and "specializing" in them?
What about in something like "$1 chips"?"

To me, there is a difference between collecting and specializing. You collect chips, but you specialize in Harrah's.

We collect Nevada Casino "darn near anything" but we don't specialize in anything in particular. (We don't collect tokens, card keys, or slot cards....but we do have some! go figure!)

If your example "collects $1 chips", that indicates to me that his/her collection IS $1 chips. If he/she "specializes in $1 chips" that indicates to me that the collection includes other things, but their main interest is the $1 chips.

"Does the term "that person specializess in... "XYZ chips" suggest to you that that person has a heightened level of knowledge about them?

Not necessarily. You can collect or specialize, without "knowing your stuff". That's the kind of collector that ebay sellers love!

"How about if they just have "more" than the average collector?"

How many does the average collector have of anything?? We have maybe 1000 chips, Was it Greg that posted chip # 10,000? Someone else might have 50,000.