analogy, analog

Analogy or analogy means a comparison of two things, based on similarity, used as a description or an explanation --
Young readers may not understand the analogy of texting styles to handwriting.
Rock stars as aristocrats is a common analogy.

Analog or analog ( also spelled analogue ) describes a varying physical signal, used to transmit varying types of information --
The modem converts the analog signal into a digital format that the computer can use.
An analog device can, theoretically, transmit infinitely variable signals.

Analog may also mean something having a similarity or correspondence to another thing--
To him, the chess board is an analog of the political world.
I'm uncomfortable with the view of a child as an analog of the parent--"a mini-me".

Now that you know that, you can say --
"The analogy of the brain and the computer is apt for some mental functions, such as memory, but for others the brain is more like an analog device."