Okay, so the red is quiet and it is smooth? is it going to be suitable for me?
No, the Red is designed for use in NASs, it's firmware is specifically developed for running 24/7 in a RAID array in a NAS box, it's probably not what you're looking for. Sure, it will work, but you pay quite a big price premuim for a Red drive for no benefit to you.
As someone above says, the Green is designed to power down after a couple of mins inactivity to save power. I'm personally not bothered by the very occcasional click as the drive spins down and the head parks.
i read that an ssd is more susceptible to wear out.
This is false. A harddrive is more likely to break down because it has moving parts. Although the flash memory in an SSD will wear out eventually, it will take decades under normal use. An average SSD will last much, much longer than an average harddrive. The big advantage of a hard drive is cost.