A Vehicle's FT weapon is like any other FT - no TH DR, just an IFT Effects DR against all Personnel, Gun & unarmored vehicle targets in the target hex. Random SW Destruction will also apply.
Vs. AFV, again there's no TH DR - just an effects DR using the FT line on the 'HE & Flame TK' table. But in this case, the AFV must be pre-designated as the target, & the attack will not affect other units in the hex.