Are small portable drives as reliable as desktop drives

Hello,
I'm need to purchase a new hard drive for backing up all my data.
My question is, with identical type usage, is a small good quality portable drive, (with smaller and possibly more delicate moving components), likely to be more prone to mechanical or other failures than a larger desktop drive of similar storage capacity.
Although I prefer the smallness of a portable drive, my first priority is the reliability.
Thank you in advance for you answers.