Java: jar and. exe?

For cross-platform support.

jar/war is not just the application executable file, it is a "package" of the application. By analogy with apk, msi, deb, etc.
In addition to executable code, jar, as a normal zip archive can contain resources, libraries, descriptors, manifests, and any other files that will need application or system that uses it.
And, as already noted, the application in this format should work on different platforms.

Probably crossplatforming
\r

java-jar some.jar and native solaris on ultraSPARC will work not only in windows x86

>Same CLR runs the EXE Nicki quietly.
\r
As far as I know, just Vice versa. Exe invokes the clr, which reads the bytecode within the Assembly. However, the same can be done with the jar file, for example, using jar2exe.