The common:

low latency, stable and reliable

The difference:

1) The application scenario is different. SRT is suitable for transmission over two different locations on the network and can traverse the Internet; NDI is suitable for LAN use.
2) The low latency of SRT refers to the low latency of transmitting protocols such as RTMP in the Internet environment, and the minimum delay can reach milliseconds. The low latency of NDI refers to the low latency of transmitting protocols such as RTSP in LAN environment. The minimum can reach the millisecond level.
3) The SRT needs to specify the listening port; the NDI can be automatically found in the LAN.
4) The transport layer protocol is different. SRT uses the UDP protocol and NDI uses the TCP protocol.
5) SRT is an open source system that is compatible with other SRT protocol devices; NDI is compatible with NDI protocol devices.