I'm old and British enough to remember a "billion" being a million million, and a "kilobyte" being 1,024 bytes. Today, a billion is a thousand million, and a kilobyte is exactly 1,000 bytes.
Wait, when did a kilobyte start meaning 1,000 bytes...?
I would suggest it's more of an ease of discussion - i.e. in general conversation the difference between 1,000 and 1,024 doesn't matter, but in industries where it does matter it would be important to ensure your calculations account for 1,024. I don't think the 'meaning' of a kilobyte has changed, and I think it's a good reflection of what we're discussing here. Perhaps to the layman who doesn't know much about movies and is not interested in making them, the correct usage of the term Foley doesn't really matter. But if you're educating those who want to make movies and those with a keen interest, and people who may eventually transition into the professional industry the correct and accurate usage should prevail and definitely matters.
For the same reason that not accounting for the extra 24 bytes per kilobyte could result in disastrous effects if you work in technology.
As for a billion, I have never heard of it being a million million...
ay that gun handling sounds are foley and the gun shot would be SFX, regardless of how they were recorded. If you recorded the sound of a rifle to replace and big up the sound of the gun shot, but did it in real-time along with the video, does that make the gun shot now foley? If the gun handling sounds were taken from a library (and huge production companies use libraries these days) does that make it SFX? Does it even make sense to have that distinction these days?
I'll defer to the audio guys as they're the specialists, but (as per my understanding), sound performed live to picture would be Foley and anything that's pre-recorded would be a sound effect. So yes, if a Foley artist recorded themselves hitting a punching bag live to picture to 'big up' the lower end of a gun shot, then that would be Foley. If the Sound Editor (Designer? Mixer? Is it just me or are all the sound-post roles blurring now..?) takes a sound from a library it is a sound effect.
The distinctions matter because they're important. Foley is a process. Sound effects are not. The placement and mixing of sound effects is a process, but Foley is a process in and of itself separate to placement and mixing. Foley has time and budgetary considerations that are different to using an SFX library. And in the end, you want to come off as a professional. You don't want to tell a Producer you're gong to use Foley, and then have them come back to you distressed telling you they've had to push deadlines and find some extra cash to get Foley artists and a stage, only to laugh at them and say 'oh no I meant sound effects, what did you think I meant?'
That Producer may not want to hire you again...