Difference between SNMP and Syslog

1. Simple Network Management Protocol (SNMP) : SNMP is an application layer protocol which has been developed to monitor network devices over IP networks. It is responsible for exchanging management information between network devices. SNMP protocol is defined by Internet Architecture Board (IAB). SNMP protocol is a part of Transmission Control Protocol/Internet Protocol (TCP/IP) protocol suite. Simple Network Management Protocol (SNMP) is used to manage and monitor network devices. This protocol collects information from different network elements and also configuration and modification take place as per required basis. 

2. System Logging Protocol (Syslog) : Syslog protocol is a widely used cross-platform for message logging. Syslog is used to collect system event information from various systems, devices, network elements and stores it in a central Syslog server. These stores Syslog data is analyzed and alerts in case of any critical events. This Syslog protocol is defined in RFC 3164 but it was initially written by Eric Allman. This Syslog protocol is designed to help in transporting these event messages. Mainly it collects various device logs and stores in Syslog server then monitors it. So simply we can say it is protocol responsible for transmitting event messages and alerting across IP networks. 
Difference between SNMP and Syslog :

Serial Number	SNMP	SYSLOG
1.	SNMP protocol refers Simple Network Management Protocol.	SYSLOG protocol refers to System Logging Protocol.
2.	It monitors the network devices over IP networks.	It transmits the log messages to Syslog server and monitors it.
3.	It traps are shared in binary format.	It events are shared in Plain text format.
4.	It is an active protocol.	It is an passive protocol.
5.	It is secure.	It is not secure.
6.	It is referred to get real time information.	It is referred to acquire historical data.
7.	It is used to alert on critical actions like mentioned (Hot Stanby Router Protocol) HSRP state changes.	It allows to dig dipper to figure out why that (Hot Stanby Router Protocol) HSRP state change occurred.
8.	By the help of SNMP end device configuration is possible.	By the help of Syslog set end device configuration is not possible.
9.	It uses UDP port number 161 and 162.	It uses TCP/UDP port number 514.