NLX has slots parallel to the motherboard as ATX does not
There are no similar form factors to ATX if you're talking about a slimline. Slimline form factors are NLX and LPX. The form factors to ATX are BTX, Micro-ATX, and Flex-ATX. There is no correlation between slimline and ATX.
NLX has expansion slots parallel to the board to allow smaller cases but may limit the number of expansion slots, rather than perpendicular like the ATX
The most popular form factors are: -Mini ITX -Micro ATX -ATX -E ATX
Some motherboard form factors (from smallest to largest in physical size) are: -Mini ITX -Micro ATX -ATX -E ATX
Before the ATX form factor was released, XT, AT, and BabyAT were the most common standard form factors.
The three form factors for desktop system boards are: ATX, and BTX and NLX
These are form factors (size and shape) of motherboards you can plug CPUs into. They have no speed in themselves. For example, both ATX and micro-ATX (there is no mini-ATX) boards are available for most recent CPUs, making them the same speed with the same CPU.The differences between them are more along the lines of the size of the case it will fit in and how many expansion slots they have.BTX hardly exists anymore, it was a form factor proposed by Intel but cancelled in 2006.If you are in the market for buying one of them, I suggest going for one of the common standards: ATX (standard desktop tower size) or micro-ATX (a bit smaller)The two ATX standards are for all practical purposes the same except for the size and the number of expansion slots.See related link for more form factors.
ATX is the main form factor of today. Other form factors are basically just variations of ATX. Example: BTX & uATX
Because it allows for maximum flexibility compared to other form factors.
ATX, MicroATX, Flex ATX, BTX, and NLX, In that order.
There's actually three: ATX, Mini ATX, and Micro ATX. The difference is only in size. Mini is about half the size, Micro is 1/3 But of course with the size, you sacrifice extra ports, usually PCI expansion ports.
AT, ATX, and BTX