A spark 'ignites'. It is a matter of oxidation (flame) or air excitation (electrical).
Ignite the Spark, Fuel the Fire: Innovative differentiation
An oxidation (flame) spark is preceded by a rise in temperature/rise in vapour pressure and an electrical spark (air excitation) is preceded by a rise in potential difference.
Technical Note :
It is impossible for a visible spark to form in a vacuum.
Electrons can jump the gap in a vacuum but they are invisible, there is no spark just a current flow.