Seems the big difference with embroidery machines is internet capability... the more expensive ones all have it. With the combos, some have it, the cheaper ones don't. Also the number of fonts supplied with the machines that don't have internet would be a consideration. And the size of the embroidery area. Cheaper machines only do a 4X4 inch area... the better machines do 5X7. Design editing is nice too. Some come with designs too.
Here's the ones I'm looking at:
Amazon.com: Brother SE400 Computerized Embroidery... Amazon.com: Brother LB6800PRW Project Runway...
They both have computer connectivity and 5 monogram fonts.
This one has no connectivity but it does have 600
stitches!
Amazon.com: SINGER 9960 Quantum Stylist... Amazon.com: Brother PE770 Embroidery Machine with...