Are Quads and ATVs the same?

Em...Strictly speaking, they are not the same. ATV is the broader category, and ATV includes Quad. Quad is a subcategory under ATV specifically referring to "four-wheeled" vehicles, because early ATVs had 3 wheels, 6 wheels, or 8 wheels, while Quad specifically refers to having four wheels.

In the 1980s, when manufacturers like Honda and Yamaha introduced 4-wheeled vehicles, in order to completely shake off the bad reputation of 3-wheelers being "easy to rollover," they spent massive advertising budgets promoting "Quad" (such as Suzuki's Quadracer series). This successfully implanted the brand identity of "Quad = safe, high-performance four-wheeler" into the minds of a generation of consumers. This commercial habit continues to this day.

As time progressed, the distinction was no longer about "counting wheels," but evolved into differences in cultural habits, industry standards, and vehicle design purposes.

For example, the UK, Europe, Australia, and New Zealand rarely use the term ATV. Media and locals alike call it Quad. However, in North America (US, Canada), ATV is the absolute dominant term officially and casually. When Americans say ATV, they mean a four-wheeler.

ATV (All-Terrain Vehicle): An official/industrial master category. Any motorized vehicle with a "straddle seat + handlebars + suitability for rough off-road terrain" is called an ATV.

Quad (4-Wheeler / Quad Bike): Literally means "four (Quad)." It specifically refers to an ATV that has exactly 4 wheels.

All Quads are ATVs, but not all ATVs are Quads.

UTV / SxS is not a Quad (because it is an off-road vehicle with side-by-side seating and a steering wheel).

Quad always refers to an ATV (i.e., Quad = 4-Wheeler ATV, a 4-wheeled straddle-seat off-road motorcycle).