We find TextDiff very useful when we write code and also to see how text documents have changed over time. Unlike most other diff text products, our software can leave out unchanged lines and paragraphs making it very easy to see just the differences. It can compare any type of text document, via copy-n-paste to its two text windows. It also supports drag-n-drop of plain text, rich text and Microsoft Word documents. Note that it will only compare the plain text part of RTF and Word documents.
Until Friday 6th November 2020, we are offering Florencesoft TextDiff for $10 USD.