Reference:https://answers.splunk.com/answers/103/transaction-vs-stats-commands.html
The stats command is faster and more efficient than the transaction command, especially in large
environments. The stats command is used to calculate summary statistics on the events, such as count, sum,
average, etc. The stats command can group events by one or more fields or by time buckets. The stats
command does not create new events from groups of events, but rather creates new fields with statistical
values. The transaction command is used to group events into transactions based on some common
characteristics, such as fields, time, or both. The transaction command creates new events from groups of
events that share one or more fields. The transaction command also creates some additional fields for each
transaction, such as duration, eventcount, startime, etc. The transaction command is slower and more
resource-intensive than the stats command because it has to process more data and create more events and
fields.