What's the difference between instop and unstop?

Instop

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Definition:

• (v. t.) To stop; to close; to make fast; as, to instop the seams.

Example Sentences:

Unstop

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Definition:

• (v. t.) To take the stopple or stopper from; as, to unstop a bottle or a cask.
• (v. t.) To free from any obstruction; to open.

Example Sentences: