As others have said, everything particulate that gets thrown out of a volcano is ejecta, but not all ejecta is ash. Lava is not ejecta unless it’s getting thrown out as bombs (large gobs of lava that get thrown out as individual particles centimeters to meters in diameter)
Large explosive eruptions have the energy to fragment the erupting magma into tiny shards – what we call ash – so big eruptions generally generate more ash.
In fact, ash is a grain size descriptor. Any fragment of erupted magmatic particle can be described as a pyroclast. Pyroclasts can be described by their gransize; anything less than 2 mm diameter are ash, anything over 64 mm are blocks, and the stuff in the middle are called lapilli.
Volcanic ash is a very different thing to ash from fires. The volcanic version is fragments of rock glass: dense, sharp, and hard. The ash you get from fires is incredibly fragile residue of whatever is left when you’ve burnt the rest of the wood/paper/fuel away. They have really no similarities.
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