Difference between “make install” and “sudo make install”

Usually I try to run it without sudo anyway - sometimes it works. Sometimes package creators think sudo is required, they use it due to their preference, or otherwise choose to install things in non-user areas of the system. Sometimes this is necessary, but many times it isn't.

The other common reason I see for the use of sudo is in blog posts by 3rd parties that explain how to install software, and rather than go the extra mile and explain to you how to install it without sudo privileges, they tell you to use sudo because the person writing the post simply uses sudo for everything, which isn't really a good idea.

Theoretically, the only reason a package should require sudo is if it needs (or decides) to install itself into/otherwise modify areas of the system that can only be modified via administrator access.

Generally speaking, fewer and fewer packages are still doing this, as the need for users to install some software without sudo access is growing.

You are correct regarding the Makefile the only things that happen are defined in it or companion scripts that get run. "Best practices" when upgrading software from source is typically to use the uninstall option if you did not run a make clean or delete your original source installation directory.

You have to be careful though, should the program have installed files outside of /usr/local you might remove files that were added by the package manager. Often main configuration files like Apache's do not get clobbered and simply deleted during installation they can or are preserved. Though this is not always the case. You can backup every destination with the -b or --backup option to install.

Edit: Looking at the Makefile.in for the current version of httpd it looks like several of their cp commands add the -p switch which preserve ownership and timestamps.