How SharePoint Lists and Libraries handle attachments

Their are many differences between a List and Library in SharePoint Online. This post only describes the differences with respect to storing and working with attachments.

Topic	Library	List
Search in attachment	When a file is stored in a Library the search will give a very accurate result of where the search term is found. In below example the search is carried out for the word “PI” and the word has been found in 2 attachments and the location of the word is displayed in the search results as well.	When the file is stored in a list the search will give the list items where the search key has been found. The search will not tell if the search string was found in a file or in the list item. The user must open the list item and check each file for the search string manually.
Versions	Version history of attachments is supported. In a Document Library it is possible to restore previous version.	Version history of attachments not supported. A major drawback of a SharePoint lists is that attachments are not versioned along with other changes to a List tem when List versioning is enabled.
Check-in/Check-Out	Supported	Not Supported
Drag and drop files	Supported	Not Supported
eDiscovery feature	Supported	List attachments will not work with the eDiscovery feature
Document Preview	Supported	Not Supported
Download copy option	Supported	Not Supported

Conclusion

To summarize; if you want to store and organize, share and collaborate on your documents then our advise is to use a SharePoint Document library.
Only use a SharePoint List occasionally and as secondary type of storage place for documents that are not accessed frequently.