They seem to be the same diodes.
The h is just mostly marketing, but also added specs in the data sheet for horticulture use.
If you read over the data sheets you will see:
Lm301b
Tech Spec
Wattage0.2 W Forward Voltage2.7 VLuminous Flux39.3 lm Luminous Efficacy223 lm/WCondition5000K, 65 mA, 25°C
Lm301h
Tech Spec
Wattage0.2 W Forward Voltage2.7 VPPF0.55 μmol/s PPE3.10 μmol/JCondition65 mA, 5000K, CRI 80
Wattage is the same, forward voltage the same. Conditions are the same so we can compare them directly. If you run the numbers through a lumen to par calculator 39.3 lumens = 0.55 μmol at 5000k
So as far as I can tell, they are the exact same chip. The H designation is so the datasheets have the required information for the horticulture guys.
That's how I see it. I'm sure Samsung would answer if we asked them.