Here is what you can do. Just check the ADD and COPY documentation for an clear description, but in short, the major difference is that ADD can do more than COPY:
- ADD allows <src> to be a URL
- If the <src> parameter of ADD is an archive in a recognised compression format, it will be unpacked
Note that the Best practices for writing Dockerfiles suggests using COPY where the magic of ADD is not required. Otherwise you (since you had to lookup this answer) are likely to get surprised someday when you mean to copy keep_this_archive_intact.tar.gz into your container, but instead you spray the contents onto your file system.
I hope it would resolve your query.