My dear. I am so sorry I am just now seeing this.
Teck and Tan are two different colors done in Natural Calfskin. Hedi's Natural Calfskin is treated much differently than Phoebe's. It depends on which era the bags you are comparing are from.
Do you mind explaining a bit more what the difference is between Heidi’s and Phoebe’s natural calfskin? I’m thinking of getting a classic in natural calfskin but don’t know if I should get a new or a pre-loved one! Thanks