What is the difference between "execution time" and "elapsed time" in the logs?

In the logs, the "execution time" is the time the query required to execute where "elapsed time" is the time from when AMPS first receives the query (it incorporates the time taken for parallel query execution).

Neither include the network trips to/from the client.

The "elapsed time" can be longer than the "execution time" for a number of reasons including that it's part of a larger parallel query, SOW delete or there could be many queries from the same client that is causing queries to be serialized.

AMPS batches queries for efficiency so the overall delivery for everyone is much faster than having the queries performed sequentially.