The differences of strokes between "氏" and "斤" are the following.
The most important difference is crossing or non-crossing for 3rd and 4th strokes.
The angle of 1st and 2nd strokes in both "氏" and "斤" is obtuse and the strokes are discrete. The 2nd stroke in "氏" has acute angle and is connected. These are 2nd important rules. Don't forget the rules.
The 2nd stroke in both looks like same in the case of hook deletion using the redundant rule.