R - POSIXct vs. POSIXlt

As I continue to learn about managing date and time data, I'm working to understand the difference between

POSIXct and POSIXlt

POSIXct is a date-time data object that stores the number of seconds since a certain point in time in the past.

POSIXlt stores a list of day, month, year, hour, minute, second, etc.

I'm still learning when best to use each type in different contexts. More to come on that.