All members of the official Zotero family (Standalone and Zotero for Firefox) use the same code, across all platforms (Windows, Mac, Linux). There are minor differences between Standalone and Zotero for Firefox, but only because Standalone does not have direct access to the browser.
Standalone and Zotero for Firefox can (and normally do) share the same data directory and database, so there is no need to pre-commit.
WIth respect to platforms, the one thing worth knowing in advance is that word processor support on the Mac (in all versions) is slower on large documents (~100+ references).
The major difference in features is that Zotero for Firefox can automatically redirect journal web sites to go through a proxy server (such as your university library). Standalone can't do that because it isn't part of the actual browser. Like fbennett says, you can set both Firefox and Standalone to use the same database, so you change your mind later or even install both and use each at different times. For example, I use Firefox when downloading articles for the proxy features, but Standalone when writing to avoid the distraction of having my web browser open when writing.
To enable it, check the "Enable proxy redirection" and "Automatically recognize proxied sources" boxes in the Proxies tab of the Zotero Preferences menu. Will manage itself then.
Upgrade Storage
Standalone and Zotero for Firefox can (and normally do) share the same data directory and database, so there is no need to pre-commit.
WIth respect to platforms, the one thing worth knowing in advance is that word processor support on the Mac (in all versions) is slower on large documents (~100+ references).
Is there anyway to do that through Chrome?