Different keys for different locks

I collected and compared the keys around me: keys that open doors in my life, in my friends' lives, and at my work. The variations in keys came from the locks they open and the importance of the places and items behind them. Simple keys open drawers of paper, small keys open bike locks, silver keys open car doors (even if they are brass underneath), and personalized (engraved or stickered) keys open apartment doors.

Differences:

1. color (gold, silver)

2. bow shape

3. blade shape

4. size

5. texture

6. material

7. dirtiness

8. amount of scratches

9. thickness

10. engraving

11. hole shape

12. hole size

13. lettering

14. logo

15. whether stamped

16. length

17. border style

18. importance

19. card or metal key

20. metal or plastic

21. labeled or unlabeled.

22. tarnished or not

23. number of teeth

24. if there's a duplicate

25. if on a key ring with other keys