Cayenne types?

Hi all…
First post.
I cannot seem to find the right information to understand from who’s perspective are the Input and Output data types. For instance I have an analog voltage measurement on the node…I seem to be able to use either CayenneLppAddAnalogOutput or CayenneLppAddAnalogInput and in either case the data shows up on mydevices…

Can someone please tell me is Output embedded calls used to send data and Input calls used to receive data? Why would both work to send data??

Thank you