...You can lose permanent residence but you cannot lose citizenship. If there is a war between your homeland and Argentina, if you are a resident you lose all your assets and you go to a concentration camp. If you are a citizen you are Argentinian for Argentina and you are a national for your country. Neither Argentina neither your country recognizes the second citizenship in its territory. This is specially true with British. I don´t know if Britain accepts to have double citizenship with Argentina. During WWII Argentina declared war to Germany when the war was almost won, Merck Industries was expropriated.
If you condemned in criminal case,
1) Over 3 years you go to jail, at 50% of you condemn there are 2 possible scenarios: a) You are a citizen, so you have the right to recover partially liberty if you had good behavior. (You can be free during the day and you go to sleep to the jail). At 66% or your condemn you might be free full time.
If you are a resident, at 50% you can chose to be deported or you are deported. But you lose your residence status.
2) Less than 3 years you might not go to jail. Having permanent residence you loose it. Being Argentinian you go home.
You don´t lose citizenship. My father was born in Chile. He became Argentinian but he was living in Sweden the last 20 years. Now he is Swedish too.
With residence you must be here once every two years if I am not wrong.