Data Science is the intersection of programming and statistics. I think the defining characteristic of being a data scientist is being able to insert a statistical tool inside a software system. Putting data science models into production is actually a very small part of my job, but I think that is what makes me a data scientist. Most of my time is spent cleaning data, trying to understand data, and making presentations to win support from business stakeholders. These tasks are also done by data analysts, but an analyst wouldn't code up a web service to receive data and return predictions.

The main software tool that a data scientist uses is either Python or R. They may use Excel, but I would never hire a data scientist that wasn't able to program in one of these languages (or maybe something similar).