In my book a battery charger is the generic term. Battery conditioner seems to have crept in to describe low current, typically <= 4amp smart (multi-mode) chargers. These may offer pulse charging but all have a float mode, usually in the order of a volt or more lower than full charge voltage, say 13.2 to 13.6 volts for lead/acid batteries.
A lead/acid battery will draw whatever charge current it needs within max current available and the battery charge voltage upper limit controlled by charger. Any smart charger left on will sooner or later will drop to float mode and can be left on safely 24/7 which will help to reduce long term sulphation, the main ageing effect.
Even on float over extended periods there will eventually be some sulphation of battery plates and/or stratification of electrolyte. Some smart chargers seek to offset this by automatically rebooting into the full charge sequence every 15 days or so. If in doubt this can be user instigated simply by turning smart charger off then on again.
