The Journey PerfectFit Elite steps up to 26 litres of storage and 3360 g of carrier weight, the extra volume and features aimed at trekking further into the wild with a child rather than short walks near the car. Compared with the base PerfectFit's 17 L and 2990 g, that's more room for spare clothing, food and gear for a longer day out.
The added weight over the base model reflects the extra features built in for backcountry use — worth it for parents planning proper treks with a child, but more carrier than needed for a quick park walk, where the lighter, smaller PerfectFit or Signature would do the job.