Background/Objectives: Oleosomes, plant-derived lipid nanostructures comprising a triacylglycerol core surrounded by a phospholipid monolayer and interfacial proteins, provide sustainable alternatives to synthetic lipid vesicles. This study compares solvent-free aqueous extractions of oleosomes from five nuts (almond, macadamia, walnut, hazelnut, pine) and five seeds (flaxseed, sunflower, hemp, sesame, canola/rapeseed) to understand how botanical origin influences composition and physicochemical behavior. Methods: Oleosomes were isolated using solvent-free aqueous extraction. Extraction yield, lipid content, protein content, particle size, polydispersity, and zeta potential were determined using standard analytical assays and dynamic light scattering techniques. SDS–PAGE was performed to evaluate interfacial protein profiles and oleosin abundance. Results: Extraction yields ranged from 8.4% (flaxseed) to 59.5% (walnut). Oleosome diameters spanned 424 nm to 3.9 µm, and all oleosome dispersions exhibited negative zeta potentials (–26 to –57 mV). SDS–PAGE revealed abundant 15–25 kDa oleosins in seed oleosomes but relatively sparse proteins in nut oleosomes. Seed oleosomes were smaller and exhibited stronger electrostatic stabilization, while nut oleosomes formed larger droplets stabilized primarily through steric interactions due to lower oleosin content. Conclusions: Variation in oleosin abundance and interfacial composition leads to distinct stabilization mechanisms in nut and seed oleosomes. These findings establish a predictive basis for tailoring oleosome size, stability, and functionality, and highlight their potential as natural nanocarriers for food, cosmetic, and pharmaceutical formulations.