I don't exactly know why you're getting downvoted, but I will point out that while they play in the same sandbox, this is roughly equivalent to suggesting that someone rewrite their app because Solr and ES have absolutely stellar differences of opinion about the API used to access them, the amount of schema one must provide up-front to the document index, and the amount of operational hoops one must jump through to keep the service alive
Sure, there are about 5-6 open source search engines one could pick from in a greenfield project, with amazing differences of features and maturity, but choosing between Open Search and ElasticSearch is likely a "political" decision, since they are (ahem, mostly) API compatible and have very similar operational needs.
Sure, there are about 5-6 open source search engines one could pick from in a greenfield project, with amazing differences of features and maturity, but choosing between Open Search and ElasticSearch is likely a "political" decision, since they are (ahem, mostly) API compatible and have very similar operational needs.