The basic meaning is the same - for something to go up to a higher level.
The difference is that raise must have a direct object (one thing is making another thing go up) whereas rise does not have a direct object (one thing is going up by itself). Here are some examples:
Something raises something else:
The student raised his hand. o The government will raise taxes. o The store is raising their prices.
Something rises:
In the morning, the sun rises.
She rose from her chair.
(She stood up)
Unemployment has risen by 10%
ne reason for the confusion is that an increase in salary is called a pay raise in American English, but a pay rise in British English.
Arise is similar to rise, but is more formal and abstract. It can also be used to mean "appear":
Several important questions arose during the meeting.
I'd like to work in Japan, if the opportunity arises.
A new spirit of hope has arisen among the country's people.
Sorry, I'll need to cancel our appointment. A few problems have arisen.