bolt of lightning vs lightning

[Daniellll]

I looked at the dictionary and i am still unclear about the difference between:"bolt of lightning" and "lightning" are these synonyms? if so why someone would want to use an extra word by mentioning "bolt'

[SoothingDave]

"Lightning" can refer to activity that happens over a period of time (minutes). A bolt of lightning or a lightning strike is one particular release of cloud-to-ground electrical energy.