What Is The Difference Between Metaprolol And Atenolol?

hi doctor i would like to know the difference between metaprolol and atenolol. which is better i mean less side effects? i am 60 years old, have been taking amtas AT since 7 years. last week when i went to a new city and a new doctor, he prescribed amtas m 50. is metaprolol latest drug in the market? obliged.