README unclear about bashreduce HOT 1 OPEN

Since this is quite old ticket, you might no longer be interested in it or already figured it out by yourself.
But I would share my understanding for future reference of other people.
bashreduce has two helper programs, brp and brm written in C. If you look into bashreduce's source, you will notice it uses brp and brm if they are installed automatically. But if not, it will fall back to awk or sort -m.
The second column shows which mode was used, coreutils=awk+sort -m or brp/brm.

Going back to your question, in the second row, awk+sort were used and in the third brp/brm were used.

from bashreduce.