Final answer:
The log record that signifies the start of a transaction's execution in database systems is called a Start record. It is different from other types such as Checkpoint, Commit, and Abort records.
Step-by-step explanation:
The type of log record that records that transaction T has started execution is known as Start log record. Log records are used in database systems to maintain a history of transactions that have occurred. The Start record indicates the beginning of a transaction's execution. Other types of log records include Checkpoint (marks a point for system recovery), Commit (indicates transaction has completed successfully), and Abort (indicates transaction has been rolled back or terminated unsuccessfully).