@Lweji - yes well in a way this is true, as HIV is a virus, & AIDS is the name used to describe a syndrome, or set of symptoms/illnesses. AIDS can also be referred to as late stage HIV. So this can be muddied in a way in that at what stage does HIV become AIDS? People infected and not on treatment generally eventually become poorly with small illnesses leading to more serious ones.
In the past many more people progressed to the AIDS stage, which I guess is why I guess both names were used interchangeably in ER. In the UK AIDS used to be defined when someone's CD4 level (type of white blood cell) dropped to under 200. An HIV neg person has a CD4 of over 500.
However, now, if a person presents with a CD4 of, say, 35, and even it they have other illnesses, they are told they have HIV - not AIDS (this is in the UK). They are put on treatment and they recover. I chat to people regularly who are diagnosed late like this, simply because they never knew, or thought to test or thought they might be at risk.
Of course it is true that in the USA the word AIDS is used a lot more. Also in countries like Africa, where it is very prevalent, and meds can be difficult to access. There are a lot of countries unfortunately where people are still dying of it.