Can you help me distinguish between the two with a little meaning? It would help a lot, thanks!

1.ESSENTIAL VS. NATURAL ELEMENTS OF CONTRACT TO SALE;

2.REAL VS. CONSENSUAL CONTRACT

3.SALE VS. CONTRACT TO SELL

4.LICIT VS ILLICIT SALE

5.EMPIO REI SPERATAE VS. EMPTIO SPEI

6.PRESENT VS. FUTURE GOODS

7.CERTAIN VS. UNCERTAIN PRICE

8.SIMULATED PRICE VS. GROSS INADEQUACY IN TH EPRICE

9.PERFECTED CONTRACT VS. CONSUMMATED CONTRACT

10. SALE BY AUCTION VS. ORDINARY SALE

11. EARNEST MONEY VS OPTION MONEY

12. SALE BY DESCRIPTION VS. SALE BY SAMPLE

13. RECTO LAW VS. MACEDA LAW

14. ABSOLUTE INCAPACITY VS. RELATIVE INCAPACITY

15. TRADITION LONGA MANUVS. TRADITIO SIMBOLICA

16. TRADITIO BREVI MANU VS. TRADITION CONSTITUTUM POSSESSORIUM

17. SALE OR RETURN VS. SALE ON APPROVAL

18. UNPAID SELLER VS UNPAID BUYER

19. EXPRESS WARRANTIES VS. IMPLIED WARRANTIES

20. WARRANTY VS CONDITION

21. HIDDEN DEFECT VS. REDHIBITORY DEFECT

22. LEGAL REDEMPTION VS. CONVENTIONAL REDEMPTION

23. ASSIGNMENT OF CREDIT VS. EQUITABLE MORTGAGE

24. GUARANTY VS. MORTGAGE

25. PACTO DE RETRO SALE VS. ORDINARY SALE