Moving The Drive From My Old Computer To My New Computer?

I bought a new computer. It works fine. I moved the hard drive from my old computer (which also works fine, but is old...) to the new computer.
The new computer says it can't find a boot drive. It can do disk diagnostics on the the drive, so it obviously can see it; but apparently doesn't recognize it as a boot drive.

So... everything works fine, but the new computer doesn't recognize the old computer's drive as a boot drive.

Is there any way around this?
I've done it a couple times in the past, so this is disappointing.

New computer is a HP 270-p043w with a 1TB drive, W10
Old computer is a HP 5F0A6CU with a 128GB SSD, W10

 

So when I got it to work in the past, I just got really lucky?

 

You could reduce the partition size on the 1TB drive. Make the Working size smaller than the SSD drive.
You would then be able to clone the newly smaller working drive onto the SSD.
Of course do make Backups of everything before you start.
s.

 

Apologies. I was just looking from the perspective of owning the equipment and where I could go with it.
Of course a fast USB3/c sata extension would be needed.
Good luck with the journey.
s.