Party, Parity 就差一个i，但意思大异奇趣。

Party - part + y。 

词根：part：部分，局部。后缀 -y - 类似“的”，比如windy, rainy。

Party可作动词，表示enjoy oneself at a party or other lively gathering, typically with drinking and music. 作名词则有两个意思：

• a social gathering of invited guests, typically involving eating, drinking, and entertainment. 聚会，一般有吃喝玩乐的聚会。
• a formally constituted political group, typically operating on a national basis, that contests elections and attempts to form or take part in a government. 政党，党派。

Parity - par + ity。

词根：par: 标准。后缀 -ity - 名词化。

指相同的状态-the state or condition of being equal, especially regarding status or pay. 比如 parity of incomes between man and woman。 男女收入均等。