Hi allan and welcome...
Let's take your antenna question first. How far away you'll hear something depends on many factors - the output power of the transmitter, the height of both the receive and transmitting antenna, the frequency and any obstructions, just to name a few.
The antenna on most scanners is, at best a compromise, and on some frequencies, likely to be little better than a wet noodle. To hear 25 miles on a consistent basis, an external antenna, mounted outdoors, is the ticket. Being that your area is basically flat, it wouldn't take too much height to accomplish this - with a proviso.
Remember I mentioned frequency as one of the criteria? In general, the higher in frequency, the shorter the distance it will travel, all things being equal. So while hearing 25 miles on a VHF hi frequency is not all that hard, at 800, that's pushing it a bit.
I want to address your scanner choice here as well. Certainly either scanner will work - however your area is not using digital all that much. Unless you plan on using the scanner when you travel, you'd be better off with an analog scanner (at least for now). We have a very active Maryland forum where I'd encourage you to ask questions about that, but if you can save some bucks to put into the antenna and coax, you're going to be better off in the long run. Digital scanners are expensive (unless you happen to get one at a used sale or off eBay, for example).
Just for future reference - keep this bookmarked - here is our database entry for Worcester County. Note that anything that's blue is usually a link
Worcester County, Maryland (MD) Scanner Frequencies and Radio Frequency Reference
and here's our Maryland forum...
Maryland Radio Discussion Forum - The RadioReference.com Forums
It would be helpful to know what your scanning targets are - that way folks can chime in with sepcific recommendations
HTH...Mike