Hi there,

Active attack:

An attacker tries to modify the content of messages. Attacker interrupts the content of message. It modifies actual information.

Passive attack:

In passive attack, an attacker observes the messages and copies them. It does not modify actual information.

Example of active attack :

session hijacking, main-in-the middle,impersonation.

Example of passive attack:

Traffic analysis and release of messages contents.

Hope it helps you

Good luck!