Battery Chargers
Smart Chargers, Switch Mode Chargers, Intelligent Chargers these are all names given to the latest generation of chargers that have a micro-processor with logic controls. They are programmed with algorithms or programs using logic like when voltage X is reached and when current reaches or reduces to X amount of Amps do this... or after X number of hours has past do this. They read voltages and currents to change from one function (stage) to another. The battery, however, is lead, it has no smarts so the smarter the logic control the more useful the charger becomes.
Marketing has led to the competition of list those stages, and now we see 7, 8, and even 9 stage chargers being used on batteries. You could argue a fixed voltage would charge a battery and in some cases that works. Or a 2 stage charger can bulk and float a battery very well like when using a solar controller. You only need 3 stages to charge a battery or cycle a battery efficiently and everything after that is meant to be a feature or benefit like maintenance mode or recondition mode and these are used to differentiate one brand while trying to promote over another brand. Internationally however all the best and biggest brands know how a battery should be charged and generally work within the same constraints outlined by the battery manufacturers so you only need to select the correct charging profile and size the current correctly for the battery bank and the charger will do its job.
Of greater importance, these days is the usage/environment, for example, in a marine environment, you use a sealed IP44 or better (higher numbers are better) rating. That the power supply doesn't de-rate in hot conditions. That the energy efficiency is a high percentage to reduce heat and chance of failure and if you travel internationally with your charger that it's rated for 110VAC input and 220VAC input (universal power supply). Accessory items are available if required and technical support is available from the place of purchase.