Padding is a non determinative way of adding some time to tasks in a project.
task 1 takes 1 day. lets put duration down as 2 since ,,,,,,,(many reasons)
Not because is is like a ball park estimate...
Buffer is more determinative.
task 1 takes 1 day. task 2 might also be done by the same person. this is identified as a possible risk. and we mitigate it by adding some time in which will be a mutually acceptable amount of time the developer feels he can reasonably finish.
acceptable because there is some quantitative/expert estimation.