While TLS is widely used for securing internet communications, SRTP is specifically designed for securing real-time multimedia content, such as voice and video calls. 

Transport Layer Security (TLS):

• Purpose: TLS is a protocol that ensures privacy and data integrity between two communicating applications on the internet. It's widely used for web browsing, email, instant messaging, and VoIP.

• Functionality: TLS encrypts the segments of network connections at the Transport Layer end-to-end. It prevents eavesdropping, tampering, and message forgery.

• Usage: Common in web browsers (HTTPS connections), securing credit card transactions, and for secure data transfer over the internet.

• Versioning: TLS has evolved through several versions, with TLS 1.3 being the latest, providing improved security and performance.
  

Secure Real-Time Transport Protocol (SRTP):

• Purpose: SRTP provides encryption, message authentication, and integrity for voice and video traffic in real-time applications.

• Functionality: It's used to protect VoIP traffic from eavesdropping and tampering, ensuring that voice and video calls remain private and secure.

• Use with VoIP: SRTP is commonly used in combination with SIP (Session Initiation Protocol) to create a secure VoIP connection.

• Key Management: SRTP typically relies on external key management protocols, such as DTLS (Datagram Transport Layer Security) or MIKEY (Multimedia Internet KEYing).
  

Both TLS and SRTP play crucial roles in protecting different types of digital communications. TLS secures general data transmission over the internet, ensuring that sensitive data like passwords and credit card numbers remain private. SRTP, on the other hand, is tailored for the specific needs of real-time voice and video communication, providing the necessary protection without significantly impacting the performance required for real-time streaming.