As can be evidenced from the motherboard size chart above, there's quite a dramatic difference in scale between Mini-ITX and MicroATX, with more of a subtle difference when comparing ATX and EATX ...

But gamers and other regular computer users may have no idea what EATX motherboard to purchase or which ones are ideal for their needs. Extended ATX commonly referred to as EATX, are bigger ...

The typical size of an ATX motherboard is about 9.6" x 12". EATX: 13" x 12" -- A fully-featured ATX motherboard with an extended width of 13" and height of 12" instead of ATX's maximum of 12" x 9. ...