The modal adverb (语气副词) expresses subjective judgment or assurance toward an action.
The adverbs 互相 and 相互 "each other, mutually" are used in a conversation about two or more objects that interact with each other.
You should get to know each other first
nǐmen xiān zìjǐ hùxiāng rènshí yíxià ba
They hate each other
tāmen xiānghù tǎoyàn
Both companies have agreed to cooperate with each other
liǎng jiā gōngsī tóngyì xiānghù xiézuò
互相 and 相互 are almost identical in usage, but there is a slight difference in their meaning:
互相 emphasizes the process of interaction, no matter what comes after it.
相互, on the contrary, emphasizes the action that comes after it.
相互 and 互相 can form the following words and phrases:
相互作用 相互支持 互相帮助 互相尊重
相互 can also be used as an adjective "mutual". It is usually followed by the particle 的 .
The feeling is mutual
shuāngfāng dōu yuànyì gùjí xiānghù de lìyì
Both sides are willing to take their mutual interests into account