The meaning is the same, the use is different :
1. In particular
is a sentence adverbial. You'll tend to find it at the beginning of a clause or an elliptical phrase, often separated from the clause by a comma: I enjoyed the exhibition. In particular, I liked the impressionist paintings.
or .... I liked the impressionist paintings in particular.
or I enjoyed the exhibition, and in particular, I liked the impressionist paintings.
or I enjoyed the exhibition, and in particular, the impressionist paintings.
It is often used in sentence initial position in written English, as in the first example.
can be used in the same way, though is more frequent with co-ordinated clauses and/or elliptical phrases, or in sentence final position. I enjoyed the exhibition, and particularly the impressionist paintings./ .... I liked the impressionist paintings particularly.
It doesn't crop up in sentence initial position in written English with the same frequency as in particular
- in fact I didn't find any examples of it used like this in the searches I did.
3. However, particularly
, being an adverb, can also be used to modify verbs, adjectives and other adverbs in a way that in particular
can't : I particularly liked the impressionist paintings./ The impressionist paintings were particularly nice. / I studied the impressionist paintings particularly carefully.
.This is perhaps the most important difference between them.
Here are some examples of each from the Cobuild concordancer
, which show those rules working. In particular
... of nuclear fuel reprocessing and in particular, the economics of the new ...
... the spread of infectious diseases, and in particular of AIDS ....
... the works of Raphael and Domenichino in particular.
.... he returned to the horses he loved, in particular, the Hackneys.
.... opposed to all innovations of any kind. In particular it was dead set against one plan ...
could always be substituted for in particular
, though it's much more unlikely in the sentence initial position of the last example and would be less likely to be followed by a comma in the penultimate example. Particularly
... a background I found particularly useful when dealing with such a range of ...
If the grapes of the year are particularly good, the half-fermented wine
Gardeners are in a particularly high-risk group, although by taking ...
... or putting forward radical ideas are particularly welcome.
He is likely to do particularly well in his work and ...
Yeah, we particularly looked out for it
Here, in particular
could never be substituted for particularly