Absolutley there is a difference between the two, but we are talking vehicles and driving here. Driving across/thru/over/under obstacles and terrain are done the same way no matter what you carry for the mission. The basic offroad and on road driving principles do not change, whether it is stock or modified only allows you to tackle a tougher obstacle or make tackling it easier.
The test is the challenge you issued in your previous post with modified jeeps and the specified #'s. Below from Wayoflife, that is a lot of weight and it seems to be proof enough when you watch any of his video, most specifically any from the "Keep it Tight" series
wayoflife
ummmm, i don't own any "play" rigs. ALL my jeeps are daily drivers. as far as weight goes, a stock JK comes in at just under 5,000 lbs. my white JK weighs in at about 6,500 lbs. unloaded. with gear, it's more like 7,000 lbs. or more.
My apologies if I came across as being upset or irritated, but this is the internet and not TV, thats why I use the emoticons available for choosing on the left when posting, so you can gauge my disposition

No hurt feelings here. But I do think you are showing a huge lack of understanding on the topic of offroading in general. My position still stands that it is all the same, you can church it up or make it more mysterious with special words, but "overlanding" and "overlanding rigs" are simply feel good words and definitions of something that did not need a new classification.
Cheers and heres to civility
G