Word count and character count both measure text length, but they answer different questions. Word count tallies whole words - the metric for essays, articles, and content-length goals. Character count tallies individual characters, which matters wherever hard limits exist: tweets, meta tags, SMS, and database fields.
Choosing the right measure keeps you within constraints. A blog post is judged by words; a meta description is judged by characters because search engines truncate at a pixel/character threshold. Knowing which limit applies prevents cut-off text and missed targets.
