Separate citizenship, current residence, possible rights through ancestry and the rules of the destination. Living in Britain does not make someone a British citizen. Holding UAE residence does not give the holder a particular passport or a general right to settle in another country. In a mixed-nationality family, make the comparison person by person.
Existing EU, EEA or Swiss rights may change the available routes before an investment programme enters the discussion. Rights through a spouse or another family relationship depend on the actual legal conditions; they are not interchangeable with the principal applicant’s passport. A possible nationality through ancestry also needs the relevant eligibility and documentation before you can rely on it.
Ireland illustrates the distinction. A British citizen’s position under the Common Travel Area differs from the position of a non-British family member joining them. UK residence alone does not confer those British rights. For EU, EEA or Swiss citizens and their eligible family members, a different legal framework may apply.