Structural and molecular properties of homopolymer and polymer-blend nanoparticles were studied via Monte Carlo simulation of coarse-grained polyethylene-like models with different interchain interactions. For stronger interchain interaction, homopolymer nanoparticles become more compacted structures accompanied by higher bulk densities with sharper surface profiles. For polymer-blend nanoparticles, chain components with weaker/stronger interchain interaction tend to stay in the surface/bulk region and their density profiles exhibit uneven distribution. Near the surface, end/middle monomers are more segregated/depleted for stronger interchain interaction., Both bond and chain exhibit relatively random orientation in the bulk region, but they have noticeably anisotropic orientation, especially near the surface. Compared to the homopolymer nanoparticles, chain components in polymer-blend structures have more distortion, mostly near the surface. For stronger interchain interaction, polymers gain a larger fraction of gauche conformation in the bulk region and nanoparticles become denser packed structures.