Answer
rRNAs are identical and tightly clustered, typical of genes meant to produce just RNA, while the globin genes are more spread out and more diverse in sequence. The former kind of multigene family provides the ability to make many, many copies of a crucial RNA, such as rRNA, while a multigene family with sequence diversity allows for multiple forms of a protein with variable function.
Work Step by Step
Both kinds of multigene family are important since some RNAs are needed in very large quantities for any active cell while other functions must take place under varying conditions (such as oxygen partial pressure) and require a diversity of protein forms to cope with those varying conditions.