Although / even though
Despite / despite the fact that
In spite of / in spite of the fact that
In theory… in practice…
But is more informal than however. It is not normally used at the beginning of a sentence.
"He works hard, but he doesn't earn much."
"He works hard. However, he doesn't earn much."
Although, despite and in spite of introduce an idea of contrast. With these words, you must have two halves of a sentence.
"Although it was cold, she went out in shorts."
"In spite of the cold, she went out in shorts."
Despite and in spite of are used in the same way as due to and owing to. They must be followed by a noun. If you want to follow them with a noun and a verb, you must use the fact that.
"Despite the fact that the company was doing badly, they took on extra employees."
Nevertheless and nonetheless mean in spite of that or anyway.
"The sea was cold, but he went swimming nevertheless." (In spite of the fact that it was cold.)
"The company is doing well. Nonetheless, they aren't going to expand this year."
While, whereas and unlike are used to show how two things are different from each other.
"While my sister has blue eyes, mine are brown."
"Taxes have gone up, whereas social security contributions have gone down."
"Unlike in the UK, the USA has cheap petrol."
In theory… in practice… show an unexpected result.
"In theory, teachers should prepare for lessons, but in practice, they often don't have enough time."