Is there a difference between these aggregations

[Aseem Bansal]

If I want to aggregate mean and subtract from my column I can do either of
the following in Spark 2.1.0 Java API. Is there any difference between
these? Couldn't find anything from reading the docs.

dataset.select(mean("mycol"))
dataset.agg(mean("mycol"))

dataset.select(avg("mycol"))
dataset.agg(avg("mycol"))