Twin room and double room are terminologies used in the acquisition of hotel rooms. You might have been hearing this, or probably making use of the terms. A major headache between these two terms is that; double refers to a room that has a large bed capable of occupying two people. Whereas, twin refers to also a room but with two little beds.
So, in a double room, the beds are together as one; while in a twin room, the beds are separated. When booking as a couple, they will most likely prefer to get a room for double, while probably two friends of either sex would go for a twin room. I believe this has really enlightened you on the difference between the two terms, and you know what kind of room exactly to book for.
Whenever you are looking for you and your spouse, you now know you should go for a double room. Also, if it is you and some without an intimate relationship, you will be going for the twin room.