They stack up generally the same, but the interface and layout are just different. Lexis and Westlaw seem to be better for case law and citations, but Practical Law is better for legislation and articles that get to the point of what I need without having to read a case.
It's best suited for in-house counsel that wishes to stay on top of recent case law and labor decisions. It's also great for labor & employment attorneys working at firms to have a high level overview of key issues. The chart builder and Daily Labor Report are the best resources for in-house counsel. The content is easy to flip to in-house client teams and department heads along with individual analysis and suggested action items.
PracticalLaw offers excellent Practice Notes, Checklists, Precedents, and Toolkits for a variety of practice areas - which is very helpful to in-house counsel and law clerks that are working on files across different practice areas. Less appropriate when there are already many resources available to me to help in drafting documents - then there is not much use to look up PLC.
Lexis Practice Advisor is an excellent alternative - but Practical Law has more comprehensive coverage of topics and practice areas - as well as more frequent updates to tools and checklists. Also, Practice Law integrates well with WestLaw which is great for having all the legal research and files centralized.