Complex sentence: It should not be confused with the current Rickmansworth on the Metropolitan Line of the London Underground which is a short distance to the north west of the site of Rickmansworth (Church Street) railway station.
Split into simpler sentences: It should not be confused with the similarly named Rickmansworth Underground station on the Metropolitan Line of the London Underground. That is a separate station a short distace to the north west of the site of Rickmansworth (Church Street) railway station.