If an attribute is selected in the <Unique ID field> parameters, features will be grouped according to values in this field. Instead of a single point with the center of mass of the whole layer, the output layer will contain a center of mass for the features in each category.
This algorithm combines two vector layer of the same geometry type into a single one.
This algorithm combines multiple vector layers of the same geometry type into a single one.
If attributes tables are different, the attribute table of the resulting layer will contain the attributes from both input layers