The difference is that SSD drives are much faster, more reliable, but also more expensive. It shouldn't be too difficult to move from an HDD to an SSD.
It's super easy. Most SSD's come with migration software, which just transfers all the data on your current hard drive to your new one. I wouldn't recommend getting a terabyte one though. You could save yourself quite a bit of money if you got a smaller SSD, and a larger secondary HDD.
In general, SSD's should be reserved for your OS and files that can't be moved to a secondary drive. You can keep all of your media and programs on a secondary drive pretty easily. Plus, when you look at the cost, large HDD's are super cheap. I just picked up a 1TB HDD for $60 last week. Even if you picked up a 4TB HDD and a 120GB SSD, you'd probably end up saving a few hundred bucks, and you'd end up with more space!
Like pandaa said, you're better off buying a small SSD and large HDD combo. Just put the OS files on the SDD and everything else on the HDD. For programs/games that you want to run quicker, install them onto the SSD.
Depending on the SSD you purchase, it may come with software from the manufacturer to help you migrate your drives over. You can also look online for freeware software to aid you in the transfer. I would recommend one that I used to upgrade my gaming laptop from a regular HDD to an SSD, but I can't remember the name. I'll see if I can dig it up.
I actually just recently discovered something new today. Called a SSHD. It seems to be at a lower price and offer a similar speed to SSDs and as much space as a HDD.
HDD is just an Hard Drive. SSD is an Solid State Drive. Both are hard drives. Solid State hard drives are better than Hard Drives.
Solid State Drives don't have the disk in it, like a normal hard drive does. So solid states are better, but much more expensive.
SSD drives can read files much faster than a normal hard drive. So that's why they put their operating system on the SSD, so that it boots their computers up faster.
I actually just recently discovered something new today. Called a SSHD. It seems to be at a lower price and offer a similar speed to SSDs and as much space as a HDD.
SSHD is a "Hybrid" drive with offers the best of both worlds. The only problem I have with the Hybrid drives is that the SSD portion is relatively small (like around 8GB). So you pretty much just have a HDD with a little speed boost. You're better off buying a standalone SSD and a standalone HDD.
SSD is more faster than traditional spinning HDD, But it very hard to get data back if it get crashed. Don't forget to backup your regularly to different media.
