The plastic ones are actual plastic kits made by Italeri. They tend to be better detailed but of course you have to construct them. Being Italeri the engineering is sometimes a bit iffy but overall they build fairly painlessly. IMO the Rubicon kits provide a better balance between ease of construction and accuracy, as they are better engineered. Most, albeit not all, of the ‘Warlord’ plastic kits are also sold by Italeri themselves, available in mainstream modelling shops and they tend to be about 2/3rds the price of the Warlord badged version, despite being the same kit.
The resin models tend to be just a few parts, typically one piece hulls, separate turret, fittings etc. Quality wise they vary from quite decent to fairly shite.