Hi, apart from being able to use more RAM, and generally perform better, the only difference from a security standpoint is that as well as avoiding address space exhaustion problems, a security feature known as ASLR (https://en.wikipedia.org/wiki/Address_space_layout_randomization) works much better in 64-bit applications than in 32-bit applications, so 64-bit Firefox will be slightly more secure.

Security Advisories for Firefox: https://www.mozilla.org/en-US/security/known-vulnerabilities/firefox/

https://blog.mozilla.org/firefox/firefox-64-default-64-bit-windows/

Thats what I looked for

It also means if a person with 32bit will still get the 32 bit.

Firefox Stub Installer https://www.mozilla.org/en-US/ and Firefox.com

Full Version Installer https://www.mozilla.org/firefox/all/ for both.

Extended Release Version for both : https://www.mozilla.org/en-US/firefox/organizations/all/ Note : Legacy Extensions will be deleted or removed in any version update after May 2018.

Please let us know if this solved your issue or if need further assistance.