1

When can we use them? Are they the same or different?

"How tall is that building?" Can I use "high" in that sentence or not?

"This is the tallest mountain in Japan." Can I use "highest" in that sentence instead of "tallest"?

0

I think "tall" would be used when you can visualize both the bottom or top of something, or when the size is greater than the average one.

How tall are you?
That building is tall.

Check the definition tall sense 1, 2 or 4.

"high" is almost always used for elevation, so I would use:

This is the highest mountain in Japan.
How high is the plane flying?

Check the definition of high sense 1, 2 or 3.

0

Tall is an adjective describing a characteristic of an object:

The man is tall.

The building is tall.

The ant is not tall.

High describes where the object is:

How high is that cloud?

Height describes a characteristic of an object:

Please record your height and weight.