Difference between Zabbix Versions

[mitul.nfdil]

Hi there, I want to know major difference between zabbix 4.x and zabbix 3.x before any upgradation.
Also want to know about different file dependencies and issues in different versions and different challenges during upgradation.
Please help.

Thanks in advance.

[StephenJ]

Here is the release notes for the different versions.

https://www.zabbix.com/rn/rn4.0.5

[Andrzej PAwlik]

I upgrade zabbix 3.2 to 4.0.3

work fine