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These are very different.
* I will pick the children up around two o'clock.
* I welcome the children (to the place) around two o'clock.
In this case, and are different. However,
* I watch a movie.
* I go and watch a movie.
These ones are not too much, one is just saying 'watch movie at anywhere', you can watch movies at home these days. Another is saying 'watch a movie in a certain place', likewise a theatre. The latter one implies, you are going out of your home and watch a movie.
is a formal expression. And sounds a casual expression. In this case, is a very popular and common phrase/term for travel almost an idiom/colloquial thing thus sounds ill-mannered or unnatural.