XDSC = Sub Compact ie little and easier to hide, less than 4 " barrel.
XD could be any of them
V10 has a ventilated barrel newbies shoukld pass on these.
XD Service 4" barrel
XD Tact probably what you want. 5" barrel
The Tactical is a full size pistol and has greater accuracy potential which is important to a newby. It is also a little heavier and therefore more stable.
The extra weight reduces felt recoil a bit.
The shorter XD's have much stronger recoil springs which makes operation a bit more difficult for smaller people.
I have owned both XD actical and Service models. They are good pistols.
Get some lessons then enjoy what you get