Is the D700 the Nikon equivalent to the 5D Mark II? I am weighting my options since where I live Nikon have better market share/service/support than Canon.

I shoot indoors/candid/events (I'm not a pro) and am looking to upgrade to a full frame camera from my current Canon 500D (1.6x)

I haven't purchased any Canon lenses (other than a basic 50mm 1.8) because I have not decided if I will stick with Canon or Nikon.

Also, if someone could please explain all the letterings in the Nikon lens lineup, for example Canon has IS = Image Stabilization, USM = In-lens focusing motor; and two types of lenses - EF for full frame, EF-S for cropped. EF lenses work on all bodies, EF-S only on crop sensors. L is their premium lens.

What's the equivalent terminology for Nikon?

So far all I can understand of Nikon's terminology is DX = crop sensor, FX = full frame.

Thank you, and I apologize if this is repeated often. I tried to search but I didn't get any hits.