Capacitive Keyboard VS Mechanical Keyboard

A friend of mine told me a story that his girlfriend wanted to purchase a mechanical keyboard for him as his birthday's present. She purchased an HHKB as she learnt HHKB is built for programmers. The HHKB she bought was capacitive. 

Is capacitive keyboard a kind of mechanical keyboard? 

Capacitive keyboard, as Deskthority's wiki explained,  is a variable conductive diode matrix with hysteresis capacitance device that was improved by J. Arthur Cencel. In this type of keyboard, pressing a key changes the capacitance of a pattern of capacitor pads. The pattern consists of two D-shaped capacitor pads for each switch, printed on a PCB and covered by a thin, insulating film of solder mask which acts as a dielectric.

Mechanical Keyboard contains a complete switch underneath each key. Each switch is composed of a housing, a spring, and a stem. Switches come in three variants: linear with consistent resistance, and tactile with a non-audible bump, or tactile with an audible click. That's why mechanical keyboard may not a good equipment in the office. One of my colleagues complained about the noise from my typing.

In fact, I used to treat capacitive keyboard as a mechanical keyboard. With the development of my vision and chatting with mechanical keyboard users, I would like quoting a geekhack member's explain,

I would define "mechanical key" is one that has:
* A "mechanism", in classic terms. There is at least two parts that together form a simple mechine, a joint, a lever, wedge, etc. and...
* This mechanism plays a part in actuation of the key.

+ A IBM Buckling Spring switch (membrane or capacitative) is mechanical because the foot pivots.
+ Cherry MX is mechanical because the plunger has an inclined plane that presses against a leaf spring.
+ Alps SKCL/SKCM is mechanical because it has a plunger that presses against a leaf spring - that is an inclined plane.
+ Fujitsu Peerless is mechanical because the coiled spring interacts with the rubber dome that it sits on!

- A scissor switch is not mechanical: there is a mechanisms but the mechanism is not used to actuate the key.
- Topre is not mechanical because there is no classic mechanism: only a sensor, which provides a value in a range.
- Linear Flaretech is not mechanical because there is only a plunger: only a sensor which provides a value in a range.

It isn't important that capacitive keyboard is a mechanical keyboard or not. The important thing is we are enjoying typing on both of them. Both of them give us typing and gaming pleasure beyond membrane.