They may all differ by the thickner that's being used. Looking at wikipedia, fumed silica is a common one. Or they could all just differ by packaging...
The plumbers grease (says 100% silicon grease) I typically use and see (Wolverine Brass) is good for up to 400F. It fits the description of having a fumed silica base but that's only speculation. It's definitely dielectric as I've used it in both of my vehicles ecm harnesses. Although I guess you could always just check the electrical conductivity with an ohm meter if you don't trust it.
Works great in caliper slide pins also, unlike normal grease it doesn't dry out.