(If you're not a fan of Kingston Technology over on Facebook, you really should be. Among other reasons, you'd learn that I'm helping out there by answering questions from readers just like you, but focused more specifically on RAM, memory, SSD drives, and similar. Check it out: Kingston on Facebook)

I asked Kingston hardware engineer Louis this same question, and here's what he explained to me:

Actually, there are a few major differences between old and new solid-state-drives (SSDs for short). For the sake of this discussion lets define Old SSDs as SATA 2.0 or earlier and newer SSDs as SATA 3.0, drives made since January 2011.

With all SSDs the controller is the "engine of the SSD" With the introduction of SATA 3.0 SSD controllers the bandwidth increased to 600MB/s which is double what SATA 2.0 SSDs were capable of and four times what SATA 1.0 SSDs could deliver. So to begin with I would say newer SSDs have significantly better performance.

The other major differentiators and advantages I would give to newer SSDs is 1.) The support of the TRIM command and 2.) better garbage collection.

Specifically, all gen 1 "older SSDs" were all known to suffer from the same problem: they'd start fast and eventually slow down. This phenomenon occurred because any NAND flash based device (USB, CF, and SSD) cannot simply write over previously deleted data but instead has to erase the old data, then write the new. This process doesn't take long but does slow down the performance of the SSDs over time.

This process is known as garbage collection and early SSDs were not very good at managing this part of high-performance storage. Most SATA 3.0 based SSDs like the Kingston V200, V+ 200, HyperX and KC100 are now programmed with an advanced garbage collection algorithm so the drives keep themselves clean and maintain consistently fast performance today, next month and next year.

The other advantage I mentioned was support of the TRIM command. This is part of the ATA command set and is somewhat related to the garbage collection process I mentioned earlier. Simply stated, when a file is deleted from the SSD the operating system will mark that area for deletion the next time the controller is moving that data. The TRIM command is great but requires OS support -- currently only Windows 7 or very recent Linux distros. A drive that does effective garbage collection really doesn't need the TRIM command and will work great with other OS's like OS X, XP, Vista and earlier Linux distros.

Very few tweaks are needed to maximize performance with the newer SSDs, the controllers are designing with the latest OS's in mind so they're already optimized. On a desktop gaming computer an SSD RAID will help performance by doubling the I/O bandwidth to over 1000MB/s. Go with a newer chipset motherboard from Intel. The 67 chipset and higher all feature an onboard SATA 3.0 controller which produces the best performance we've ever tested in our labs.

To summarize, the biggest difference between old and new SSD is the controller design and the performance advantages it brings. The only advantage I can think of that older SSDs may have over newer is better compatibility with some of the older more obscure very early SATA 1.0 chipsets from the early DDR1 and DDR2 DRAM based systems from 5 to 6 years ago and older.

Otherwise, it's time to upgrade!