What's the difference between a heart attack and angina

Hi. three months ago my husband was taken to hospital & diagnosed with having had a heart attack. He was prescribed Bisoprolol 2.5mg - Atorvastatin 20mg - Aspirin 7.5mg After a few weeks a consultant rang him to talk through his symptoms.He was fitted with a 24hr heart monitor, he then visited the Cardio unit to have a hand held scan of his torso. This week he has been to our local surgery to have his blood pressure taken. After which he received a phone call from our G.Pwho said that it was Angina not a heart attack. The Atorvastatin dose has been increased to 40mg. What is the difference between angina & a heart attack. ? Does he need to carry a spray with him ( hasn't been prescribed ) ? If he has another attack how do you know when it's serious enough to call an ambulance. ? He is 76yrs old, does a lot of walking, before this he was very fit & was not on any medication.