Physics suggests that resin should have a lower THC:CBD ratio, since THC boils at 157C and CBD at 180 (though some sources indicate it's boiling point may be lower) - the heat of the burning weed will vaporize all of the cannabinoids that don't undergo combustion, but the ones that are less volitile should condense more readily on the walls of the pipe. I'm not sure how large an effect this is, since the overall process is probably effected more by mass transport between the smoke stream and the boundary layer along the walls of the pipe, and this should be similar between the two.
This suggests that, if anything, resin should produce less of a head high than the weed that created it, since higher THC:CBD ratios are associated with a headier high - but the effects should be largely similar to the weed from whence it came.
HOWEVER, if the cannabis has high levels of THCV (levels vary from near trace, up to >50% - so this greatly depends on which strain you have), which partially blockades CB1, this effect might be reversed, since THCV has lower boiling point than THC.
In addition to this, we have some confounding effects:
* Strength of resin varies greatly depending on where in the pipe it is taken from, due to different levels of particulate contamination - this makes it easy to get higher than expected, which might throw off estimates of how heady the weed is.
* It's widely observed that cross tolerance between different strains of weed is not complete - and since the resin probably came from multiple batches of weed, it could seem stronger or different for that reason
* When you are desperate enough to smoke what is generally considered a waste product, you're probably dry, and may not have been smoking as much (or at all) lately, for lack of weed - which could lower tolerance a bit and thus and lead to a stronger headier high.
So, to recap - there is definitely physical justification for this effect, but it could go either way depending on the weed, and the postulated mechanism may not actually be significant.