According to the "Financial Institutions" reading, what is the main difference between mutual funds and exchange$-$traded funds $($ETFs$)?$

Question $4$ options:

$1)$

ETFs are not diversified

$2)$

Mutual funds are not traded on exchanges

$3)$

ETFs have different pricing and tax consequences

$4)$

Mutual funds cannot invest in bonds

$5)$

ETFs are only available to institutional investors