High drain
batteries can discharge their electricity at a higher rate than others and are made from a chemistry that has higher tolerances for several challenging states (such as over heat, over-discharge etc) and that discharges less hydrogen if they fail in a thermal state. So, they tend not to explode or vent with flame if they are in a failure state (because they vent very little flammable gas). IMR is the most common high-drain type of battery.
Protected
batteries are usually lithium ion
batteries with a protection circuit added to them. There are different kinds of protection circuits, but usually the protection is designed to shut down the battery if there is a short or if they are put in an over-discharge state. So, if they are discharging more amps then they are designed to, the circuit switches to off - or if there is a short, the circuit switches to off.
Hope that helps without getting too deep in to the technical and chemistry aspect of it. There is a lot of information about these kinds of batteries available from the search box.