It sounds as if you are a little confused about what an embroidery machine does. Most computerized sewing machines do some fancy stitches but you have to hand guide them into particular designs. An embroidery machine uses set patterns that create a picture or design using either one color thread or multiple to create a picture. The finished product looks like "hand embroidery". Those machines are now able to do designs or "pictures" up to 5x7 inches in size or larger if you have the right hoop and patience to make a larger design. I own two such machines and both are stand alone. They only do embroidery.
Most machine brands now sell combination machines that require you to change your sewing machine to embroidery by adding or subtracting sections of the machine. Under those circumstances you can sew or embroider but not do both at the same time.
I prefer the seperate machines because they allow me to sew on my sewing machine while the embroidery machine is sewing out a design. The embroidery machine does not require you to hold down a pedal in order to run the machine. It simply has a start and stop button. It also stops automatically when it needs to have the color of thread changed.
If you simply want to use "decorative stitches" on your quilts there are plenty of computerized sewing machines in various prices ranges that will do that well. If you really want an embroidery machine I recommend the one I most recently purchased a Brother PE780D. It came with preloaded Disney motifs as well as several sets of alphabets, frames to use for special stuff and more than 100 other things you can sew out on it. From animals and birds to stuff that looks like counted cross stitch. It cost between $700 and $900 and uses either a USB stick or the little cards. It uses the PES format. My other embroidery machine is almost 20 years old and uses the same PES format so I can use the software from it on my newer machine. I sometimes have both embroidery machines going while I am sewing on my sewing machine.