You're right.
At first the I removed the disk in my portable so that I could use it in my desktop PC, then I had to give the PC to a friend far away from me, so I removed the hard drive and put it back into the portable casing.
I then tried the very same portable on my TV and laptop, but the laptop can only detect it in the Disk/Computer Management.
Later I read about the MBR and GPT partition styles and then I decided to come here for aid, ?.
I hope we're on the same page now, ??.