The Aadhaar letter is a laminated paper document, while the Aadhaar PVC Card is a durable PVC-based card with enhanced security features. Both are equally valid.
UIDAI update: Now, order Aadhaar PVC for entire family with one mobile number; here’s how - The Aadhaar PVC from UIDAI is a version of the identity document with added security features and can be physically carried by a cardholder.
UIDAI informed the customer that he can order an Aadhaar PVC card online, instead. “You can also take a print of your e-Aadhaar if you wish to keep it in a flexible paper format."