Amazon Comprehend is AWS's natural language processing (NLP) service that uses machine learning to find insights and relationships in text. It can analyze text to identify entities, key phrases, language, sentiments, and other common elements in documents.

• Amazon Lex is used for building conversational interfaces using voice and text
• Amazon Rekognition is for image and video analysis
• Amazon Translate is for language translation

Amazon Comprehend specifically focuses on natural language understanding and processing tasks like entity recognition, sentiment analysis, and topic modeling.