It's an interesting - but gray - area. ICAO PANS-ATM says:
8.6.5.2 When vectoring an IFR flight, the radar controller shall issue clearances such that the prescribed obstacle clearance will exist at all times until the aircraft reaches the point where the pilot will resume own navigation. When necessary, the minimum radar vectoring altitude shall include a correction for low temperature effect.
It also defines Radar vectoring as the provision of navigational guidance to aircraft in the form of specific headings, based on the use of radar.
So, according to the strict definition used by ICAO, I'm not sure that a 'direct to' clearance is vectoring.
As bookworm says, in the UK we have slightly more defined rules but remember that in the UK many more IFR flights take place outside controlled airspace than (I think) in other States and, as far as I recall, the radar advisory and radar information services, certainly in the way we do them in the UK, are pretty much unique to the UK. But, of course, we only need these services because we don't have controlled airspace protecting all IFR routes etc.