A bit too hard to tell from the pictures. Not all bees have pollen baskets, actually most do not. Many native bees carry their pollen under their abdomens on special hairs called scopa, like this.
Also male bees do not have any structures for carrying pollen, since they don't need to provision a nest.
As far as size goes, bees, wasps, and flies come in all shapes and sizes, so size isn't really a good indicator.
Some general tips for telling bees from other similar insects. Flies have short, stubby antennae, have 2 wings instead of 4, and many have spongey mouthparts (although some do not) and larger eyes (although many male bees have these too). Wasps vs. bees can be trickier. Wasps tend to be less hairy and more slender. Although wasps eat meat, many are also nectar drinkers and so will visit flowers just like bees. They however do not collect pollen (and neither do flies), so if you see pollen on baskets or scopa, it's definitely a bee.