Are despite and in spite of interchangeable? I prefer despite but the alternative sometimes scans better.
a) Despite the age difference, she decided to marry him.
b) Despite being twenty years younger, she decided to marry him.
c) Despite the fact that she was 20 years younger, they got married.
d) Despite their age difference, they decided to get married.
in spite of
a) In spite of the age difference, she decided to marry him.
b) In spite of being twenty years younger, she decided to marry him
c) In spite of the fact that she was 20 years younger, they got married.
d) In spite of their age difference, they decided to get married.
I would argue that in spite of and despite are interchangeable and their position can be either at the beginning of the sentence or in the middle. The only difference being that in spite of is a longer expression and requires an additional preposition, of. Despite does not require of and as a result is shorter.
Consequently, in sentences (b), (c) and (d) I would opt for "despite". But that is my opinion, and either way they are all grammatically correct.
Yes they are. But despite seems to the one commonly used. In spite of was more popular in the past, but according to this Google Ngram it's use has been in decline.
While both terms are synonymous with notwithstanding and without regard to, they also both can convey an element of defiance or contempt. A downside of "in spite of" (in addition to being longer) is that it's potentially more ambiguous.
Consider: "I invited John to join me on my trip to the Department of Motor Vehicles to renew my driver's license, in spite of his having had an affair with my wife last year."
Or: "In spite of his having defeated me in the election, I invited him to dinner to experience my wife's cooking."
I would opt for despite whenever there could be any ambiguity.
PS: The "wife" references are gratuitous. I grew up on Henny Youngman jokes.