Compare Two Tables Query Result

dear all
i need to write SQL Query that compares 2 tables as folows:
lets say i have:
table A with A.A, A.B, A.C columns (Table A with Columns A,B,C)
table B with B.A, B.B, B.C columns (Table B with Columns A,B,C)

i need to compare and to mark (get in result Query) each row lets say in table B that was changed from table A

For Example
Table A
A B C
12 15 hello
15 17 adv
asd 19 23
14 rer 89



Table B
A B C
12 15 hello
15 19 adv
*** 19 23
14 rer 89

the result is the records which was changed from A to B

A B C
15 19 adv
*** 19 23


Thnks alot!