So, I had to order a new tire and two new tubes via Amazon after a screw disabled my road bike.

Though I ordered a pair of tubes of the same size and from the same distributor, they came in two different boxes. One is labeled: 700X20-25c. The other: 700X18-23C.

The tube I currently have on my bike is 700X18X23C-27X1. So, I'm assuming the 2nd tube size is correct; however, they both appear to be the exact same dimensions. Are my eyes failing me? Will the 1st tube work or do I need to return it?

Don't worry about it, and the important mesure is your tire width. As long as the largest figure on the tube width is smaller or equal to the tire width (700x25c for instance) you're fine. Best not to go too much smaller as the tube will be thinner when inflated, and although you can get away with the tube being a bit larger in width it's best to do so only in a pinch (pun intended).

Sweet. Thanks. I wasn't sure if the size difference would lead to something like pinch flats. Something I'm all too familiar with due to only inflating my tires to 40 psi for the first couple of months I had my bike. I know. Pretty stupid but all I was going on was feel - like I did when I had a bike as a kid. Thanks for the advice.

I used to import tubes. My supplier produced 700c tubes in 7 widths, so their OEM customers could have the best possible easiest to mount fit. Of course I wasn't going to stock 7 sizes, so I picked 4 widths and had the boxes marked for a size range.

That's how the tube world works, The tire/tube company let's the client buy whichever he wants, and put anything he wants on the box. What's surprising is that a single source had 2 such similar marked sizes in stock, but more that he was so tactless to send 2 different boxes to fill a single line on an order. Even if the tubes inside are identical, why invite questions or concerns.

Yeah, the labeling is kind of casual when viewed by the consumer.

One thing to know about comparing tubes is that the most accurate width measurement will be made with the airless tube flattened, then you can add 10 or 20% to that figure to know what the largest size tire (actual inflated size of tire) that is still safe.
Or, you could do like I do and put a flat-measured 26mm tube (labeled 20-28mm / 1-1/8") into your 23mm tires, for a slower loss of air when you puncture.

Most "standard road" (racing) tubes, the narrowest tubes available, will measure 22-26mm wide flat.
These will have labels ranging from 700X20 to 700X28, which may or may not correspond to the comparative width of the labeled tube.

Believe it or not, I've been sent batches of tires which were all of the same size yet bore slightly different size labeling, with some even having two different size designations on the same tire (one printed on, the other molded in raised letters)!!!

It's a jungle out there.