Linguistic connection between the geophysical “bluff” and the deceptive “bluff”?

Question

I know that words can have their etymology independent of words that share the same spelling, but according to Etymology Dictionary, both the geophysical "Bluff" and the deceptive "Bluff" originate in the Dutch language. But... what is the linguistic connection between them?

The first usage is the geophysical bluff:

"broad, vertical cliff," 1680s, from bluff (adj.) "with a broad, flat front" (1620s), a sailors' word, probably from Dutch blaf "flat, broad." Apparently a North Sea nautical term for ships with flat vertical bows, later extended to landscape features

The deceptive bluff: seems to relate to poker and bragging.

How do cliffs & the action of deceiving relate? Is it because they are both dangerous/risky? Or that a lie is as big as a mount?

Do we know the semantic drift and the historical relationship?

Answer 1

The deceptive bluff comes from the Middle Dutch bluffen meaning to swell or brag.

The geophysical bluff comes from the Middle Low German blaff meaning smooth.

Perhaps they may be related through the process of the wrinkled surface of something which is inflated becomes smooth.

Answer 2

If one actually bothers to read the Etymonline entry linked by the OP:

bluff (v.) 1839, American English, poker term, perhaps from Dutch bluffen "to brag, boast," or verbluffen "to baffle, mislead."

bluff (n.1) "broad, vertical cliff," 1680s, from bluff (adj.) "with a broad, flat front" (1620s), a sailors' word, probably from Dutch blaf "flat, broad."

They both come from Dutch, but that's about all they have in common.