Why does this left item provide more recovery than this right item?

Solution 1:

Recovery is a measure of how many effective hit points (EHP) you regenerate per second. It depends on both what was earlier called Healing (how much literal Life you recover) and damage mitigation.

The item on the right provides approximately the same Toughness, but structure of character's toughness changes - you have more Life, but less Resistance. So, despite your Healing recovering the same amount of Life as before, each of those hit points is less resistant to incoming damage, an hence worth less EHP.

Higher damage mitigation (Resistance, Armor, Dodge, Blocking, and other special effects) does effectively increase your Recovery by making your raw Life points worth more effective hit points.