A rope is a rope is a rope. But pick the wrong one for the job at hand and you'll understand why this just isn't true. Like with most things, there is a right tool for the job and there is a wrong tool for the job. Ropes are similar in that they are long and can be laid straight. Here's where it gets interesting, however:
We have probably all seen a ball of yellow rope. It's kinky looking, it doesn't lie flat when you try to roll it out and it isn't very strong. It also can't make a knot worth anything, that knot will just unravel faster than you can tie it. So why is it a useful rope? Well, it is waterproof and it will float. If you tip your canoe and need a rope, this thing will be bobbing around beside you waiting to be of some use. Oh, and it's inexpensive so make sure you have some around.
Climbing ropes are those made for climbing. That's easy enough, but they have a kernmantle design which is great because it makes them strong, resistant to abrasion and the best part – stretchy. No, it's not like elastic, but they do stretch a little bit which is great if you want to use them to tie down heavy loads or use to tie awkward things like poles together and keep them together.
If you want a stretchy rope, then a bungee cord is what you are looking for. These things are very stretchy and they are great to keep things rolled up when you're not using them to jump from great heights. Bungee ropes also come in a variety of different diameters so you can find the perfect one for whatever you need it for quite easily.
Braided ropes come in single or double braided varieties. A single braid will have a hollow core and will become flat when you push on it. A double braid however has a braided core which makes it stronger and less likely to kink when you are using it.
And then there's parachute cord, the 550 cord, so named because it has a minimum breaking strength of 550 lbs. It is made from a braided sheath that has up to 9 interwoven strands of separate cord inside. It's strong, it's durable and it's to military specifications. No wonder they use it when they're heading out of a plane.
A rope isn't just a rope after all!