The most important distinction on an investment-migration website is the legal outcome. Citizenship, temporary residence and permanent residence are not interchangeable.
Citizenship
Citizenship creates nationality status after approval and completion of the programme requirements. The Caribbean programmes and Turkey are examples on this site.
Residence
Residence permits allow the holder to live, and sometimes work or study, under the conditions of the permit. Portugal, Greece, Italy, Hungary and the UAE fall into this broad category.
Permanent residence
Permanent residence can provide an indefinite or durable right to reside while still remaining distinct from nationality. Malta MPRP and Cyprus investor immigration are examples.
Future citizenship
Never imply that buying a residence permit guarantees a future passport. Naturalisation usually has physical-presence, language, integration, good-character and other requirements that can change.