Basic doubts keel line vs base line

what is the difference between keel line and base line.

Seems to me base line is horizontal line at zero level, keel line can have some inclination angle and often places below zero level.

Baseline: A line in the longitudinal plane of symmetry of the ship’s hull parallel to the designed summer load waterline, which is used as a datum in defining the heights of points on the hull, and defines the primary axis of the coordinate system. Preferably, it shall be positioned such that no point on the moulded surface of the hull will lie below the baseline and shall normally be defined to pass through the lowest point on the moulded surface between the perpendiculars.

The moulded keel line would be the line that defines the upper surface of the keel plate. The keel line is often the same as baseline, but doesn’t have to be. For example, the keel does not need to be designed to be parallel to the waterline.

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Why are we answering a 5-year old question?