Deciding whether to use a decorative knob or decorative door lever is partly an aesthetic choice and partly a practical and ergonomic decision. The aesthetic part is self-explanatory and we offer all of our door handles as either round contained knobs or more expansive flowing levers.
The other deciding factor is the user’s ability to easily grip and turn a knob. A lever is by its design easier to use for those with physical challenges and this brings us to discussing the latch mechanism.
Difference between the latch mechanism for passageway knobs and levers
The tubular latch used to operate a passageway lever has a stronger spring that serves to return the lever to a horizontal position. The latch can also only operate the passageway lever one way, so one depresses it to release the tongue of the latch but you cannot lift the lever to retract the latch. The lever can be depressed with minimal dexterity and precision making it a better candidate for ADA compliance.
By comparison, a knob latch can be turned in 2 directions clockwise and anti-clockwise to retract the latch tongue but gripping and turning the knob does place some torque on ones wrist as well as requiring dexterous fingers for gripping. The spring used to return the knob to its resting point is weaker as knobs are typically lighter in weight than their counterpart levers.