different between trailhead vs railhead

English

trail +? head

trailhead (plural trailheads)

The beginning of a trail, often specifically a hiking trail.
(gaming) The initial clue that leads to an alternate reality game.
Synonym: rabbit hole
- 2017, Sangkyun Kim, Kibong Song, Barbara Lockee, John Burton, Gamification in Learning and Education, Springer (?ISBN), page 27:
  The trailhead can be exposed to potential gamers through social network services, websites, emails, or sometimes non-electronic media.

rail +? head

railhead (plural railheads)

(rail transport) A point on a railway system where goods (or passengers) are loaded, unloaded or transferred to other transport.
The furthest point on a railroad/railway under construction to which rails have been laid.
(rail transport) The top surface (head) of a rail.
Alternative form: rail head
(military) An area of hostile territory at the end of a rail line that, when captured, serves for the continuous movement into position of further troops and material.

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