Array Placement blueprint works similarly to Blender array modifier, It allows you to place number of elements in a row with relative, custom, object spacing. and fill out the desired length with equal spacing between items.
Array Spline Placement blueprint allows you to place items on the spline points, fill length with equal spacing between elements or with declared distance.
Array Circle Placement blueprint allows you to place several items on circle or arch.
Pro Spline Actor allows you to place several items on one spline and decide how it will end, start, set additional mesh at points and set offset from spline.