What are the main difference between these two motherboards?

Ferrariassassin

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Jul 3, 2014
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I own a XFX TS 550W PSU, a R9-280, a set of G.Skill SNiper series (2X4=8GB) (1600) RAM, an i5-4690, One Samsung 840 Evo 120GB SSD,and one WD Black 1TB HDD. So i have almost all of my components but i am still having so much trouble deciding on a Motherboard. The main one i like so far is the AsRock H97M Pro4, know it is a Micro but it is cheap, supports Haswell, and even has an optical Audio Out which i need a lot. The other option i have found is the AsRock H97 Killer which is $20 more and it is not micro but i am wondering it it is worth the extra $? I do not intend to adding any more expansions to my Build such as another GPU, nor will i overclock anything. I mean i may add a WiFi card but i intend to stick with an Ethernet connection for better reliability. Also the Killer says it has M.2, what is that? I guess i am wondering will the H97M Pro4 work great with all of my PC parts i listed above?