Normal log : Normal log is used for log the entire information of the system if you define that component after some other component inside that log file it actually returns the message entire which comes from earlier component it logs message information.

Cloud log: It displays the HTML messages and also we can use this cloud log for success and failure rows of an integration by using cloud log content variable which is define as a store component. 

For reference check this link:

https://community-content.workday.com/content/workday-community/en-us/kits-and-tools/products/platform-and-product-extensions/integrations/use-cloud-log-instead-of-integration-messages.html