Python DB API - commit() v. execute("commit transaction")?

[Skip Montanaro]

Assuming the underlying database supports transactions, is there any
difference between calling the commit() method on the connection and
calling the execute method on the cursor with the "commit transaction"
statement? It seems a bit asymmetric to me to start a transaction with

  cur.execute("begin transaction")

but end it with

  conn.commit()

Thx,

Skip