The data loaders use different methods of gathering data, depending on the types of data sources from which the data loaders gather data.
A data collecting loader has full control over what data is gathered from the data sources.
A data retrieving loader does not have full control over what data is gathered and needs to send a request to the data sources. The data sources send the requested set of logs or events back to the data loader.
A data sampling loader does not have full control over what data is gathered and needs to send a request to the data sources. The data sources send the requested system status information back to the data loader.