The main difference between Huel Powder and Huel Essential is the macronutrient split.
Huel Powder: 37:30:30:3 (Carbs:Fat:Protein:Fibre)
Huel Essential: 56:20:20:4
Per 400 kcal serving:
Carbs: 39g (Powder) vs. 57g (Essential)
Protein: 30g (Powder) vs. 20g (Essential)
Both are excellent sources of plant-based protein, but Huel Essential has a higher carbohydrate content and slightly more fibre.