B wrote:

In terms of color, texture, and cost, please compare and contrast
the concrete that comes in a bag with the ready-mixed concrete
from a truck. I want to add a 4 square yard extension to an
existing driveway that was poured by the ready-mix truck.

If you intend to make or pour a batch of concrete beyond a certain
amount, then making/mixing your own concrete is out of the question
anyways.

Because you are even considering bagged pre-mix, I assume you don't
have your own mixer (because if you did, you'd be considering making
your own concrete out of sand, stone, and bagged CEMEMT, which is a
lot cheaper than pre-mix).

4 square yards (I assume 4" thick) is 12 square feet. About 1/3 of a
cubic yard. That's a small job for a ready-mix delivery.

Even with a (small) electric mixer (making 1.25 cubic feet per batch)
it will take 15 minutes per batch to mix and pour. If you're very
fast and work full-tilt, you're looking at 2.5 hours of continuous
mixing and pouring. And you'll have to work fast - you don't want
part of the slab to set while you're still mixing the last few
batches.

If this is going to be 1 solid slab, then you're going to have a hard
time finishing it unless you've got some help (that know how to finish
concrete).

If you're going to do it yourself, and you're going to use bags of
pre-mix, you'll probably need 31 bags (each being 50 lbs). I'd rent a
5 or 7 cubic-foot mixer in this case.