[apohn]

IME, this is the difference.

Data Engineers are the people who take raw data (e.g. what lands in S3) and put that into data systems that can be used by other systems (e.g. Dashboards) and people (e.g. Analyst, Data Scientists, BI people). Data Engineers clean data, but they are really looking at cleaning out systemic issues (e.g. some data that is missing in one field is in another field, and that needs to be consolidated) and not the scrutinized row-by-row cleaning that Data Scientists end up doing. Data Engineers also do the data steps (e.g. creating a performant stored query) required to support things like business KPIs and reporting.

ML Engineering has a lot more variety based on the company and org, but generally it's about building an automated pipeline that includes ML. In smaller orgs you do everything - build a data pipeline, train a model, deploy that model, score new data, etc. In larger orgs, ML Engineers take a model built by somebody else and make it run at scale while meeting certain SLAs (e.g. making recommendations on a social media website).