Bromine has a softer, slightly sweeter smell than chlorine. Here is the chemistry behind the difference and what each smell tells you.
Both chlorine and bromine have characteristic smells, but they are very different. Chlorine smells sharp and chemical. Bromine smells softer, slightly sweet, and less penetrating. The difference comes from the by-products each one creates after killing organics.
With chlorine, the smell you notice is rarely the chlorine itself. It is chloramines, the compounds chlorine forms with sweat and oils. Chloramines are volatile and irritating.
With bromine, the equivalent compounds are bromamines. They are still active sanitisers (unlike chloramines, which are essentially spent chlorine), and they are far less volatile. Less volatile means less smell.
A strong chlorine smell almost always means chloramines have built up and the water needs a shock. The free chlorine reading will usually be lower than expected.
A strong bromine smell is rarer and usually just means the water level has climbed above 8 ppm. Drop a couple of bromine tablets out of the feeder for a day and the level naturally falls.
A neutral, faintly fresh smell from either is the goal. If you cannot smell anything at all, also check that you have not run out of sanitiser.
Indoor or partially enclosed UK installations build up smell faster because the gases do not vent. Bromine is much kinder in those settings.
Sensitive noses (often the same households with sensitive skin) find bromine far more pleasant.
Hot tub events: if you regularly host friends in the tub, the lower smell signature of bromine means the conversation does not get derailed by complaints about the chlorine.
Both are safe at the recommended levels. The difference is in by-product comfort, not safety.
With practice, yes. The sharper, eye-irritating smell is chlorine plus chloramines. The softer, slightly sweet smell is bromine. The cleanest smell is a properly balanced tub of either.