My diet:
Comparison

Methylcellulose vs Hydroxypropyl methylcellulose

The short answer
They're close cousins with the same safety profile. Methylcellulose sets into a firmer gel when hot, which is why plant burgers use it. HPMC forms a softer gel and stretchier films, which suits gluten-free bread and capsules.
Side by sideMethylcelluloseHydroxypropyl methylcellulose (HPMC)
Safety score86/100 Generally safe86/100 Generally safe
Gel when heatedFirmSoft
Best atBinding plant burgersGluten-free bread, capsules
Made fromWood or cotton celluloseWood or cotton cellulose
Net carbsNoneNone
Safety score8686

Swapping one for the other

For home baking, psyllium husk does a similar job in gluten-free bread, and ground flax or chia binds veggie burgers.

Common questions

Can I swap one for the other?

Often, in baking. For burgers that hold together on the grill, methylcellulose works better.