There are sites which provide an extensive information resource for the 7x10, 7x12 and 7x14 mini metal lathes. There is a site which is intended primarily to help new and prospective owners understand the capabilities, limitations and frustrations of these tools and how to modify and fine-tune them to get results you might expect only from a much more expensive lathe.
The designations 7x10, 7x12 and 7x14 refer to the maximum diameter and length (in inches) of a work piece that the lathe can work on. All three lathes can rotate a 7" diameter work piece up to approximately 10, 12, or 14 inches long, depending on the model.
Specific features of these lathes are continually being improved by the manufacturer. Early experimenters determined that the minimum speed could be reduced through some tweaking of the controls, but this is no longer necessary since the speed control on the newer machines is much improved and has a minimum speed of about 40 RPM.
The newer lathes also include some improved safety features over the older ones. They are re-branded by several vendors, painted in a variety of colors and sold with various combinations of accessories and with three bed lengths: 8", 12" and 14", but all are basically the same lathe. Best is to use 12" lathe as it finds use in most times.