How to express words variants in Chinese?
Words variants in Chinese are 异形词.

For example, there is a document published by the govenment of PRC, 《第一批异形词整理表》(The First Series of Standardized Forms of Words with Non-standardized Variant Forms).

However, I think 歺厅/餐厅 is not a typical example of “异形词”.

In fact, 歺 is one of the second round of simplified Chinese characters (第二批简化字, 二简字), which is obsolete and non-standard now. The different between 歺厅 and 餐厅 is on the character, not the word. So in this example we may say:


  歺厅的“歺”字是“餐”的二简字。


Better examples of “异形词” can be:


树阴 vs 树荫
唯一 vs 惟一