Appearance: The overall size of Micro ATX is smaller than that of ATX. Micro ATX motherboards can be installed in Micro ATX/ATX while ATX boards can only use in ATX. Considering the needs of most ordinary users, 90% of PC manufacturers may only need a Micro-ATX board.
Function: micro atx is more streamlined than ATX motherboards in function and expandability, such as PCI slots, micro atx generally provides 1, at most 2.
Target Group: Micro-ATX is smaller in size, and does not have a lot of space to install complex cooling systems or many expansion slots (memory, board cards, etc.), so integrated chipsets are generally used, which is more suitable for the users with demands on size of the host or the cost of the motherboard. The MATX boards has plenty of space to choose a variety of chipsets and different expansion slots, radiator settings, and onboard chips due to its large size. AMD ITX mobo is for general users.