After being convinced by my cousin that I needed to try out WoW, I proceeded to try and sign up for a trial, which brings us up to the first point. Cost.
RuneScape has a standard free edition for $0 and $6 US for the P2P version. In WoW, the free trial has a bunch of limitations, but none are listed up front. I was half way through downloading it when spling, from RuneScript, offered to lend me an account, which brings me to the second point.
The second extremely major difference is the set class/race/faction in WoW, whereas in RuneScape there are no such rules. It's difficult for one who has never dealt with such things as myself to handle. After reading about a zillion pages on guides, I made a mage.
In terms of a learning curve, RuneScape is faster no doubt. You can quickly fight stuff by clicking, and until higher levels all you need is food and a mouse. And honestly, there is much less to learn in RuneScape, but this becomes evident much later.
I started out with a mage and received quests, that with voice acting seemed much more real, although they had no real plot to speak of. Almost all of the quests I did were 'kill x of blah' or 'get x of blah from a monster'. I missed this from RuneScape, where although quests may not have voice acting, or nice little pop up windows, you do much more problem solving. The other thing that I really enjoyed about quests is it gave you direction on what to do, and it never felt like “I am killing furbolgs for the next 4000 exp.”
Continuing onwards, I finally realized you could buy skills, which took me by surprise. I actually enjoyed this as at least early on you could get all the skills. However skills are expensive if you are low level'd and don 't have funding from another account. You can, however learn trades which help you make money at extreme rates. It is sort of like flax collection, but to me, skinning which I did went along well. I'd kill a bear for a quest and skin it. Overall, I felt like although combat was the focus, all of the skills were extremely well thought out. (Admittedly, I never tried the production skills, as they actually cost money to get)
I continued to train, and found that as levels went on I got bored, but I never thought that I was grinding. Lots of skills, combinations of skills, and great party interfaces helped pass the time. After I obtained level 30, I Tried to play with my cousin's level 80 account. I was totally lost, and had no idea what to do. so he played on it. From watching this it really does seem to be what I've been told, RuneScape is about getting levels, WoW is about how you get them.
Performance wise RuneScape is much more dependent on internet than WoW. I found that I actually had less lag on WoW on a fast computer, than RuneScape on a fast computer, as I have slow internet.
Graphics wise, WoW wins in all aspects.
Also the controls were very different. Using the arrow keys and having the ability to jump and swim, along with keyboard spells made the whole thing way more immersive.
After my month at playing WoW, I can personally say I like the experience of playing it better than RuneScape. But that doesn't mean I'll switch over at all. The high expenses of WoW, plus the time commitment you seem to be making is really high. It also depends on how much money one has: if I had lots of time, and lots of money I would play WoW.
Coming back to the final point it seems that comparing both games in the same categories is futile. They are so unique in so many different ways, that much of it will come down to personal preference. Those interested in spending $15/month for a game should check it out, but the rest of us casual gamers can stay away.