Hi can anyone help me what is the difference between a video card with agp 4x slot and a agp 8x slot?

i have a computer with a accelerated graphics port agp 4x slot and i found a video card with agp 8x slot will that work or is there a difference|||Most all AGP8X cards will work fine in an AGP4X slot, but performance will suffer from the slower bus speed.|||Hi. The slots are identical, but one operates at twice the speed of a 4x.|||Yes the 8x card is backwards compatible with the 4x slot. It should work fine.