Difference between PGP and S/MIME

1. Pretty Good Privacy (PGP) : PGP is an open source software package that is designed for the purpose of email security. Phil Zimmerman developed it. It provides the basic or fundamental needs of cryptography. In this multiple steps such are taken to secure the email, these are,

1. Confidentiality
2. Authentication
3. Compression
4. Resemble
5. Segmentation
6. E-mail compatibility 

2. Secure/Multipurpose Internet Mail Extension (S/MIME) : S/MIME is a security-enhanced version of Multipurpose Internet Mail Extension (MIME). In this, public key cryptography is used for digital sign, encrypt or decrypt the email. User acquires a public-private key pair with a trusted authority and then makes appropriate use of those keys with email applications. 
Difference between PGP and S/MIME :

S.NO	PGP	S/MIME
1.	It is designed for processing the plain texts	While it is designed to process email as well as many multimedia files.
2.	PGP is less costly as compared to S/MIME.	While S/MIME is comparatively expensive.
3.	PGP is good for personal as well as office use.	While it is good for industrial use.
4.	PGP is less efficient than S/MIME.	While it is more efficient than PGP.
5.	It depends on user key exchange.	Whereas it relies on a hierarchically valid certificate for key exchange.
6.	PGP is comparatively less convenient.	While it is more convenient than PGP due to the secure transformation of all the applications.
7.	PGP contains 4096 public keys.	While it contains only 1024 public keys.
8.	PGP is the standard for strong encryption.	While it is also the standard for strong encryption but has some drawbacks.
9.	PGP is also be used in VPNs.	While it is not used in VPNs, it is only used in email services.
10.	PGP uses Diffie hellman digital signature.	While it uses Elgamal digital signature.
11.	In PGP Trust is established using Web of Trust.	In S/MIME Trust is established using Public Key Infrastructure.
12.	PGP doen’t  provides authentication.	S/MIME provides authentication.
13.	PGP is used for   Securing text messages only.	S/MIME is used for Securing Messages and attachments.
14.	Their is less use of PGP in industry .	While S/MIME is widely used in industry.
15.	Convenience of PGP is low.	Convenience of S/MIME is High.
16.	Administrative overhead of PGP is high.	Administrative overhead of S/MIME is low.