Twease is recommended when searching for articles about a specific subject. For instance, when searching for articles about a protein-protein interaction, we found Twease results to be three times more precise as PubMed in the top 20 hits.

The text snippets shown by Twease also make it easy to see how a retrieved abstract matches the query. Precision of those snippets, also called passages, was evaluated in the TREC genomics track and found to be among the top 20 research systems evaluated (see http://trec.nist.gov/pubs/trec15/papers/weill-cornell.geo.final.pdf).
To the best of my knowledge, none of the systems in the top 20 are publicly available for searching Medline, except for Twease.

Finally, Twease offers query by example, which is not found in PubMed. When references are collected (see Saved References above), clicking on the “Related articles” link will query for abstracts that look like the ones collected, as a group.

In summary, evaluations suggests that Twease works well to find abstracts and passages relevant to a user query, but Twease also offers innovative features not found in other Medline search engines. Hope that answers your questions, if not, please feel free to write anybody in the Twease team. We’ll be glad to provide a preprint that describe these points in greater detail.