Persons is very rare in normal English speech. Mostly you only come across it in legal or other "official" contexts such as...
The defendant conspired with a person or persons unknown to blow up the House of Lords.
6 persons maximum/Licensed to carry 4 persons (notices on lifts/taxis).
In most normal contexts the plural of person is people. When making a restaurant booking, for example, you'd normally ask for a table for six people - if you said six persons that would suggest you're nervous, unfamiliar with such situations, and foolishly trying to sound "correct" in an inappropriate context. If it was a swanky restaurant they might just say they're fully booked because you sounded gauche.
Individuals is also relatively uncommon in speech, tending again to be restricted to official (particularly, written) contexts. Probably because of this, if you said you saw four individuals somewhere, it might well imply four suspicious-looking characters, since the phrasing is typical of witnesses giving evidence in court, rather than everyday conversation.
Note that individuals carries no connotations of each individual being significantly different to every other. Identical twins wearing similar clothes are still two individuals, if the context permits using the term at all.
There's more on this subject in Person, Persons, People, Peoples, which was asked previously on ELU, but for most purposes I suggest it's enough to note that the standard forms are person/people.
Both are understandable.
I've mostly heard the following used:
Is the girl coming or are the boys?
Are the boys coming or is the girl?
An implicit difference is in emphasis, the more preferred of the options would be mentioned first, i.e. preference for the girl showing up :
Is the girl coming or the boys?
Best Answer
Here's an edited version of a post I did for ELU on a similar question (which got closed):
The existential construction takes there as a subject. There has no meaning, and often the verb takes its agreement from the complement of the verb BE. So if the Noun Phrase after BE is plural, the verb will usually be in a plural form. If the Noun Phrase is singular it will usually be singular:
Notice, however, that in the examples above, the subject and the verb BE are not contracted. In normal speech these will nearly always be contracted. We will use there's instead of there is. It is also quite common nowadays to see them contracted in writing, normally in informal texts, although you can find instances in prestigious newspapers like the Times, for example.
Now when the subject there and BE are contracted like this, the verb doesn't need to agree in any way with the following Noun Phrase. Therefore with regard to the Original Poster's example, if they had said:
... this sentence would be regarded as ungrammatical by most, if not all speakers. However because they did contract there and BE, it is grammatical:
This makes this sentence similar to a famous lyric from one of John Lennon's songs:
Or usages such as:
Having said this, despite the fact that this is a well documented aspect of the grammar, some prescriptivists are bound to take offense at this. They will insist that it's ungrammatical to use a plural noun after there's. This will be despite the fact that they quite subconsciously actually use plural nouns after there's themselves quite frequently. They will appear about five minutes after I post this answer. They do make life fun though!
There are some other special situations where we might use there is with a plural noun phrase, even though it is not contracted. For example How many people live in your house? Well, there is me, my grandad, my mum and my aunt. If you'd like to read about these exceptions, there's some good posts here!.