When we can use degree? And also when we can use level? Are they similar or not?
For example in this sentence
The way to tell a true unit from a degree of something is to look at the zero point.
Can I use level instead of degree?
Very short answer: No, you must use the word degree.
Long answer: My best guess is that this sentence comes from a high-school physics textbook.
"The way to tell a true unit from a degree of something is to look at the zero point".
In this sentence, the word "degree" is being used to mean "those units of measurement which take the word degree", (degrees Celcius, degrees Fahrenheit, etc). It is contrasting these units with "true units", (metres, feet, amps, etc), which do not take the word "degree".
We don't say "degrees feet" or "degrees tonnes", but should say "degrees celcius" or "degrees Fahrenheit". Why? Your sentence tells you: by looking at the zero point.
A quantity expressed in a true unit, -- such as a metre, second, foot, or amp, -- is such that zero means that there is nothing-at-all of a thing.
Zero metres is identical to zero feet, or zero inches, or zero light-years, it means no distance at all. Zero tonnes, zero grains and zero ounces are similarly equal, and represent a lack of weight. These are true units.
In some cases, "nothing at all" of a thing is hard to find or inconvenient to use. The classic case of this is temperature, where "no temperature at all" is hard to create or find in nature. In such cases zero must be placed rather arbitrarily and negative quantities admitted. Zero degrees Fahrenheit is not zero degrees Celcius and neither represent a lack of temperature. They therefore have "degrees" in front of them. They are so marked because there are considerable implications to this arbitrary positioning of zero.
So the way to tell if something should take the word "degree" is to look at what zero means. If it means none-at-all of a thing then it may be a true unit. If zero has been placed by convention at an (often convenient) point then it is a degree unit and not a true unit at all.
Ex: Temperature today's Phnom Penh is 40 Celsius. It is the most highest degree that I hate. Ex: I teach level1 in my class. Your case: The way to tell the truth unit from a degree of something is to look at the zero point.
You can not say "the way to tell the truth unit from a level of something is to look at the zero point." "Level" of sea "Level A1,Level B1"...refers to the level of your coursebook.
"Zero point" doesn't mean level but it means the degree of the truth unit.