Those are the same thing. Regular Arduinos use 8 bit microcontrollers. The Uno, Mini, Nano, and most other boards use the ATMega 328P chip. Typically it runs at 8 to 16 MHz. It's got 32K bytes of Flash memory for your program, and 2K of RAM for variables. That's not a lot, but with 8 & 16 bit instructions, a lot of code fits in. The lack of RAM is why regular Arduinos are not good for video or audio. Well, that, and 16MHz is kinda slow these days.
Some Arduinos use the ATMega 32u4, (Leonardo, Micro) or ATMega 2650 chips (Mega.) These expand on the capabilities of the 328, but still run slow, and they don't have that much more memory.
The SAM## Arm Cortex M## chips (it sounds like an aristocratic Spanish surname) is a family of 32 bit chips that runs much faster, and has much more memory, both Flash and RAM. All of these chips are made by Microchip Corp.
The 32 bit Arduinos do have enough power to do video and audio. Because they are newer, there is less code already written for them. All of these chips (as well as some members of Michrchip's ATTiny family) can be programmed with the Arduino IDE software.