When working at a soldering level, a solder joint is the same as a connection. Larger than that and the word, "joint" is not used. It is merely a figure of speech, not a technical term for a special kind of connection.
It depends on the application. I often regard electrical engineering as power engineering.
The nomenclature 'joint' is often with respect to a distribution conductor being terminated. A 'connection' can often be referred to as a conductor being terminated at the consumer level.
As you can see, the words mean different things depending on the context and the area of specialization. To that degree, they classify as "jargon".
When thinking of circuits, I tend to think of a "joint" as being something permanent (as in a solder joint) and a "connection" as being something temporary (as in, made using connectors). But I don't insist on those interpretations when communicating with someone else and let the context of the discussion clue me to what is actually meant.
I agree with much in the above responses. My interpretation of the term 'connection' is that it connotes any electrically conductive situation but a 'joint' is a connection with mechanical stability added.
Consider the difference between a wire sitting loosely in a hole on a circuit board making contact with the plating or pad versus the same wire when soldered.