What does it indicate? What's the difference?
The MIT and BSD licenses were drafted before software patents were common. Therefore, they completely ignore the topic. For users of MIT- or BSD-licensed software, this creates the risk of a kind of submarine patents. A rights holder could release software involving patented technology under such an open-source license, and later try to sue users for their patent violation.
This absence of any mentions of patents has been construed by some as an implicit patent license. If someone releases software to the public, then surely they must have intended for that software to be used by the public, despite any patents? Although not completely unreasonable, that is a rather shaky argument. Some kinds of implied patent licenses have been upheld by U.S. courts. However, that observation ignores that open source is a global phenomenon, and most users (including myself) are not under the jurisdictions of U.S. courts.
Some projects have clarified the MIT and BSD licenses with an explicit patent grant. For example, React from Facebook used to be licensed under the BSD + a separate patent license between 2014 and 2017. The terms of this patent grant disproportionally favoured Facebook over users and made the combined license incompatible with many other open source licenses. After a few rounds of user outcries, they relicensed under a standard MIT license, without any explicit patent grant.
The Apache 2.0 License (and later the GPL 3) introduced an explicit patent grant to the user that only terminates if that user starts any patent litigation that claims that the licensed work were infringing. This approach improves clarity through an explicit patent grant and deters patent trolling, thus protecting other contributors and users. In my opinion, this makes the Apache 2.0 license vastly preferable to licenses like ISC, MIT, or BSD variants that ignore patents.
According to RedHat, who happens to be a prominent participant in FOSS IP litigation, the clauses
to deal in the Software without restriction and
including without limitation already expressly grants patent rights, at least under US law.