What is the difference between a thunderstorm and thundershower?

Question

What is the difference between a thunderstorm and thundershower?

Answer 1

a thunderstorm has lighting and possible isolated tornadoes in them.

thundershowers only have like light periods of rain and thunder, no lightning or tornadoes or anything severe.

Answer 2

Intensity for one, heavy rain for the other. Thundershowers usually do not warrant weather watches and warnings due to the fact that they do not develop the wind gusts, torrential downpours, and possible hail that thunderstorms do. I hope this helps.

Answer 3

There is no difference.  It's just what some people prefer to call it.  A thunderstorm is often short-lived, just as the name thundershower might suggest.  

The weather service has stopped using the term thundershower altogether to avoid confusion over the terms (see the attached link from NOAA.  Some TV meteorologists might still use the term but it's now an arcane name.