Reliable Hard Drive Laptop Which Hard Drive Is More Likely To Fail?

Which hard drive is more likely to fail? - reliable hard drive laptop

My HP notebook has a 250GB hard gig, and I have a terabyte external hard drive SimpleTech bought it recently and started with my laptop. I have a lot of files, but I'm afraid that is lost if the drive could not be sometime in the future. I need to know that the hard drive is more reliable. Is my laptop hard drive is more likely to fail, or my external hard disk is doomed to failure?