The term “package” can mean different things in different file transfer situations.
“Installation package” – A file that contains all the executables, installation scripts and other data needed to install a particular application. This file is usually a compressed file and is often a self-extracting compressed file.
“Package sent to another person” – Very similar in scope to email’s “message with attachments”. This is a term that has rapidly gained acceptance (since about 2008) to describe what gets sent in “person-to-person” transmission. A package may contain zero or more files and a plain or richly formatted text message as its payload. A package will also always contain system-specific metadata such as sender/receiver identity, access control attributes, time-to-live information and quality of service information.
“Installation package” is the earlier context of the term “package” ; if you’re dealing with server teams or transmission specialists who deal primarily with system-to-system transfers then “installation package” is probably what they mean when they say “package”.
“Package sent to another person” has evolved as file transfer vendors gradually align the terminology of person-to-person file transfers with physical parcel transfers like those done by UPS or FedEx. In physical parcel transfers, individual packages may contain a variety of things but each is specifically addressed, guaranteed to be delivered safely and intact and each has its own level of service (e.g., 2nd day vs. overnight). The term “packages” is similarly used with many person-to-person file transfer solutions to help non-technical people understand the concept in a different context.