Very similar, but some differences. The components on the Jr. Gent are slightly tapered, whereas the Baron's components are the same size. That's within the same piece - the cap has a taper and so does the body.
IMHO, no kit is all that difficult; once you've mastered a slimline, you can do any other kit. The Baron/Jr. Gent make really nice looking pens, and you can get a variety of platings at different prices, so it's worth jumping in. Also, I'd only order one or two of the cheaper platings, and save your money for the good stuff...the cheaper platings just don't last long enough (regardless of the manufacturer or the plating) to make them a good long-term value.