The auto-bolding of query terms in responses is quite convenient and has allowed me to skip annoying little regexes many times. Maybe other engines have it too and I never noticed?
Rambling on, Solr is an Apache product, does tandem releases with Apache Lucene, big sister of Elasticsearch. ES used/uses Apache Lucene too as underlying database.
Especially ElasticSearch is rather fiddly and demanding, and I've seen exactly one production ES-system that impressed me, the rest were log-stores that could have used just about any database engine.
With Manticore I just apt it in and start pouring data into it immediately. Similar to how MySQL/MariaDB is almost frictionless when you run it locally with a root account, and neither ever starts to be annoying in resource consumption unless I actively mess up. I typically chose either (or DuckDB) when I have an idea or some ETL task I'd like to implement, over Postgres and ElasticSearch.