How does Façade differ from Adapter?

Facade and Adapter really are similar: both create a layer between the client and the system, but they solve different problems.

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#1. Purpose

• Facade simplifies working with an already compatible, but complex, system. → makes the interface simpler.
• Adapter makes incompatible interfaces compatible. → makes the interface fit.

Example:

• A facade hides dozens of classes behind it (VideoConverter instead of Codec, Reader, Mixer).
• An adapter fits an old class (OldPlayer) to a new interface (MediaPlayer).

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#2. Context of Use

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#3. Relationship with the System

• Facade works with the internal components of a single system - it is an outer shell around a complex module.
• Adapter connects two different systems that have different interfaces.

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#4. Changing the Interface

• Facade leaves the subsystems' interfaces unchanged, simply combining them into a simplified entry point.
• Adapter translates one interface into another.

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#5. Analogy

• Facade is like a hotel reception desk: you don't see the inner workings, you just deal with one staff member.
• Adapter is like a power plug converter: it makes incompatible plugs compatible.

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#6. Conclusion

Summary: Facade is about simplifying interaction, Adapter is about compatibility between different interfaces.