Any difference between Hardware RAID and Software RAID?

• Software Vs Hardware RAID in general; also at Serverfault.
• Short RAID 1 discussion (CentOS context).
• Serverfault: Build a software raid 1 on windows XP might also be useful for software RAID 1.
• Serverfault: How do I differentiate “fake RAID” from real RAID?

A few obvious differences:

• With software RAID you are limited to the SATA ports on your motherboard. Some RAID cards allow, say, 10 SATA drives to be connected.
• Software RAID uses additional CPU time, whereas a hardware RAID offloads such processing onto the RAID card. It depends on how you use the RAID, but this probably wont add significant load (CPU's are rather fast now..)
• Software RAID is infinitely cheaper, since it's (probably) included with your OS already
• A software RAID is more portable, tied to a specific operating system, rather than a specific RAID card brand or model ("RAID interoperability")
• (Personal opinion) Slightly unfounded, but I trust software RAID more than then drivers for RAID cards - software engineers are generally better at making software than hardware engineers!

One isn't better than the other - both have their advantages..

If you're concerned about performance, or need more drives than your motherboard will take, you should go with a RAID card (although it's worth trying/benchmarking software RAID before you buy a RAID card)

Hardware usually has better support for hotswap with separate hardware logic/circuitry, easier identification of failed drives by blinking lights, bootable volumes for any raid level and so on... performance-wise? Not really, as long as there're cpu-cycles left and the software implementation is good enough...

...but as nik has pointed out - hardware isn't always "hardware" and generally "it depends".