Having spent a few years at a large energy company, I got quite used to the use of FTP servers to exchange--what else--csv files with data. And is a uploading/downloading a file to/from some ftp server really that different from POST/GETing an object to/from some REST service?
Some major news/market information provider solely made their data available to us through ftp. And used Amazon SNS to push a notification that something new is available on that ftp.
I used a SOAP service once, which had a single string-typed element. In that element went some XML, encoded as an XML string. I found out later that the original version used FTP drops, and all they did is wrap the FTP'd file as a string in the SOAP request.
So no, sometimes there's very little difference between the two. FTP is just another way to send data over a network. I mean, you could even write a custom FTP server that read the file directly into processing instead of dropping it on a file system and reading it from there in some other process.
Some major news/market information provider solely made their data available to us through ftp. And used Amazon SNS to push a notification that something new is available on that ftp.