I think it often depends on how large the team is. On a team with many developers per model, ML Engineer to me means someone who does the engineering to support

I think it often depends on how large the team is. On a team with many developers per model, ML Engineer to me means someone who does the engineering to support models and is distinct from a researcher or a scientist. ML engineers will not do the science side of the equation (model architectures, optimizing scientific metrics like accuracy) except for when their engineering work impacts the science side (e.g. figuring out how to optimize model throughput without impacting scientific metrics). On smaller teams, the titles mean less - but I rarely see ML engineer positions for small teams. ML involves both science and engineering. ML engineer by definition sits on the engineering side of the fence, but how much of the science they are involved in will vary by company.