The current definitions in the docs are:
FreeFloat: The amount of time during which the start or finish of a task may be varied without any effect on the overall programme of work. It is a calculated elapsed time value.
TotalFloat: The difference between the duration available to carry out a task and the scheduled duration of the task. It is a calculated elapsed time value.
The definitions seem to be swapped. The proper definition should be:
TotalFloat: the amount of time that a task can be delayed without causing a delay to the project completion date.
FreeFloat: the amount of time that a task can be delayed without causing a delay to subsequent tasks.