When I called the plumber to see what it would cost to have him do this (this is a plumber that has done work for us before) he gave me his answer and then said - "please choose a faucet from a plumbing supplier rather than Home Depot. The Home Depot ones are for threaded pipes and it will take twice as long to install and the price would be different."

I went to the local plumbing showroom that he recommended and it's all fine - the prices are the same as I wanted to pay and I wasn't married to any particular style.

The salesperson at the showroom said they have the commerical lines in lieu of the residential lines, but she said it only matters for the tub - the sink faucets are all the same.

I looked on Moen and Delta's websites and I can't figure out what the difference is between the two. Does anyone know what the difference is (what are threaded pipes?) and how could you possibly tell without someone telling you?

Usually metal pipes with a tapered female 'iron pipe thread.

They can be connected to just about any plumbing pipe method (copper sweat, CPVC, PEX, etc.) by using adapters that screw in and provide the correct fitting for the chosen pipe.

It can add an adapter at every pipe connection in and out of the valve (often four, hot in, cold in, shower out, tub spout out).