what is the difference between ETA procedure and ETB

According to GUIDELINES FOR OWNERS/OPERATORS ON PREPARING EMERGENCY TOWING PROCEDURES :

• Ship-specific Emergency Towing Procedures should be identified during the ship’s evaluation and entered accordingly in the ETB. ETP is a set of rules and guidelines required to be carried out in case if emergency towing required
• The Emergency Towing Booklet (ETB) should be ship specific and be presented in a clear, concise and ready-to-use format (booklet, plan, poster, etc.). All procedures developed (ETP) ... should be presented in a clear and easy to understand format, which will aid their smooth and swift application in an emergency situation.