Emergency medicine and First aid

Emergency medicine noun - The branch of medicine concerned with the prompt diagnosis and treatment of injuries or trauma or sudden illness.

First aid and emergency medicine are semantically related. In some cases you can use "First aid" instead a noun phrase "Emergency medicine".

First aid noun - Emergency care given before regular medical aid can be obtained.

Emergency medicine and first aid are semantically related. You can use "Emergency medicine" instead a noun phrase "First aid".