Trying to reply but I'm unable to paste text or links 😤
Take a look at the Wikipedia page for legato then look at the guitar section ☺
Or go to the YouTube and search for 'legato guitar' 🎸
If speed = shredding then there's no difference if you use a technique based on legarto.
Funnily enough if I shred on guitar, I have to pick each note. But on bass I'm a fingers player and can use legarto.