Road Cycling - 25c vs 23c tires

I have 700x25c tires and I'm needing some new ones. I'm usually able to find better prices on 23c. Aside from the tire width, should I be concerned at all about different sizes. What are some advantages/disadvantages. If my rims will hold 25's, will they hold 23's? How do I find out?

TIA

Your wheels will accept either. Just make sure to get something that is puncture resistant. Lots of tires have the kevlar belts now, to prevent punctures. 23's are narrower obviously. You wont notice any difference between the two. The difference is very minor.

will I notice a difference between 28's and 23's? I have 28s now, and I also need new tires and wanted to try smaller.

The first difference you will notice is how much easier it is to remove and replace your wheels with a 23. Fit through the brakes much better. Contact area on a 23 is slightly small than a 25 which is slightly smaller than a 28, etc. Slightly lower rolling resistance with the smaller tire. You might notice a stiffer ride between the 23 and 28. 23 will also roll/ride straighter and corner better than either of the larger tires. And you can pump them to a higher pressure to enhance this, as well.

The 'real' biggest difference will be in the hills. The 23 will be considerably lighter and will be easier to ride up hills. The rotating mass makes a big difference in riding hills. The amount of work you expend includes spinning that additional weight for every revolution of your tires. Front and back. Adds up pretty quickly. That is why light wheels/tires for the hills are the ticket. Lots of graphite wheels used by climbers.