This article gives a brief description of how incremental crawls and full crawls differ.
Both Solr and Microsoft Search providers perform two types of crawls, incremental and full. Incremental crawls are typically performed when small adjustments have been made, such as content edits or new content has been added, etc.
Full crawls take place when large adjustments are made, such as folder properties, XML configuration changes, etc.
At this time, there is no way to stop an incremental crawl/any crawl from occurring. When performing a sync, a crawl will then occur afterwards. This is default functionality of the product.