Since UD attaches subordinating and coordinating conjunctions to the subsequent conjunct, this results in them being positioned in the same conjunct they relate (e.g., After will be included in the first conjunct in "After arriving home, John went to sleep"; and will be included in the second conjunct in "John and Mary").
uCCA places conjunctions as siblings to their conjuncts (e.g., "[After] [arriving home], [John went to sleep]" and "[John] [and] [Mary]").