Could someone explain "low quality smoothing" versus "upscaling" for me on a 4k TV?

[MutantMike]

So I am in the market for a new 4k TV and watch A LOT of older TV that I assume is just like 480P. Looks pretty good


What I DO NOT want is a TV that messes with it a lot, will keep it original like my DVD's look


So do I need to pay close attention to "smoothing" and "upscaling" on RTINGS?


Maybe since I want my older TV to look like intended on my DVD's, I want something that DOES NOT smooth?


I am new but wanted to ask the experts since this is a huge deal for me