Some users have recently had their accounts hijacked. It seems that the now defunct EVGA forums might have compromised your password there and seems many are using the same PW here. We would suggest you UPDATE YOUR PASSWORD and TURN ON 2FA for your account here to further secure it. None of the compromised accounts had 2FA turned on.
Once you have enabled 2FA, your account will be updated soon to show a badge, letting other members know that you use 2FA to protect your account. This should be beneficial for everyone that uses FSFT.
Both drives are probably identical on the insides, but their interface to the rest of the computer is different.
The first uses Ultra ATA-100, a parallel interface you're probably familiar with. It uses the ubiquitous 40-pin connector and ribbon cable. It has Master/Slave configurations. This drive is compatible with like 99.999% of computers in existence.
The second uses Serial ATA-150, a serial interface, and a new one at that. This drive uses a smaller connector and cable assembly. The connector looks vaguely like a USB connector, and the cable is a thin cable not unlike that of a telephone cable. Serial ATA is a new technology that allows hard drives to use a smaller, longer cable, and even connect/disconnect drives at any time. In the distant future, Serial ATA will allow hard drives to perform faster than their Ultra ATA counterparts, due to the updated serial technology. You'll need a Serial ATA controller card, or a motherboard that supports Serial ATA devices.
There is a negligable performance difference between the two drives, if any, and both drives have the same basic functionality. If you have any other questions, feel free to ask. And welcome to the forums.