Hi,
TV

When I purchased my first LED TV in 2018 I didn't know the difference between HD Ready & Full HD. I know that I should have researched the topic but fact is I didn't. The sales guy told me that the actual difference between a HD Ready & a Full HD is so little that I won't be able to tell the difference from a certain distance so I (like an idiot) went for a 39" 720p TV.

PC Monitor
My previous monitor went bad a year ago. Although the fact that by now I know what HD ready and Full HD means I simply was too short in cash to buy a 1080p monitor so I purchased a 18.5" Acer 720p monitor.

While people are upgrading from Full HD to 4K & 8K I downgraded to 720p!!!

Lol. I have a full 4K PC monitor and 2 4K LED TVs. I can definitely tell the difference but the wife can’t. She can tell the difference when she views an OLED and a standard 4K, which surprised me. She normally doesn’t care what the picture looks like.

My TV is much larger then my computer screen (which is "only" 25.5 inch), but of a lower resolution as the TV is HD 1920×1080 while my Samsung SyncMaster is 1920x1200
So when I use my TV as a screen I have to downgrade my resolution too (to 1080)!

That salesman was probably quite accurate. Unless you like to sit really close to your 39" TV, you won't be able to differentiate between SD and HD.
A 72" TV would make the SD/HD question more in favour of HD.

So while a HD monitor (for a PC) is good, a HD TV should be bought for features that have nothing to do with HD.