To look something over is to examine it.
- You should get an editor to look over this document.
- Please look over these letters. They might contain spelling or grammar mistakes.
- I don’t think that you should take these symptoms lightly. You should have the doctor look you over. (= You should get yourself examined by the doctor.)
To overlook something is to fail to notice it. Note that you can overlook somebody or something deliberately or accidentally.
- We can no longer afford to overlook his indiscretions.
- Safety checks cannot be overlooked because they could lead to accidents.
- The indulgent mom always overlooks her son’s shortcomings.
Overlook can also mean have a view of something from above.
- They have bought a house that overlooks a beautiful lake. (= They can get a view of the lake from their house.)