Telescoping = pop a pin, lift arms swing freely. Pic attached.
Turnbuckle = as name implies, twist one way to lengthen, other to shorten.
It's a lot easier to swap implements with telescoping bars. Telescoping bars require no tools. Telescoping maintain their length setting. Telescoping can be set to limit or allow a bit of play by selecting round or slotted holes to drop the pins through. Using the round holes limits the sideplay almost entirely. With telescoping, it's a snap to shift the implement's position behind the tractor.
Telescoping disadvantage, let me think. OK, you can lose the pins?
I have one tractor w/ turnbuckles, and another w/ telescoping. IMHO, telescoping is a dream compared with turnbuckles...................chim