Different references serve different purposes
A general dictionary explains current language, while a competitive word list is designed to define which spellings are playable under a specific ruleset.
Regional lists can differ
North American and international competitions may rely on different official lexicons. A word accepted in one environment may be rejected in another.
Proper nouns and punctuation
Many word games exclude proper nouns, hyphenated forms, abbreviations, or words requiring apostrophes even when those forms appear in general references.
Editions change
Official lists are revised. New words can be added and disputed entries can change status, so old printed references may not match current play.
Verify high-stakes plays
If a word matters in tournament or scored play, check the official source required by that event rather than relying on a general-purpose website.
Keep practicing
Apply the ideas in this guide with the Word Unscrambler, Anagram Solver, or Wordle Helper.