Ammonia and ammonium are obviously different from each other. Ammonia contains just one nitrogen and three hydrogens and ammonium contains one nitrogen and four hydrogens. Ammonia is known to be a weak type of base. Ammonium is ionized and can also be considered as stable.
There are a lot of people who are familiar with ammonia mainly because this is what people use to rouse people who have fainted. Some may refer to this as “smelling salts.” This comes with a powerful scent that will be enough to make people wake up. It should be remembered that the ammonium will always come with an anion while the ammonia will not have any.