Where does 'investing' end and 'trading' start?

Historically, equity fund managers have held shares for a few years, but that timeframe has been going down for the past 40 years. The average holding period for a US-listed stock was less than two years in the 1990s and, with the exception of 2019, has been under one year since 2000. Therefore, now is legitimate time to ask: when does ‘investing’ end and ‘trading’ start?