Algae, bryophytes, pteridophytes, gymnosperms, and angiosperms are different plant groups that vary in their characteristics, including their presence of vascular tissue, seed production, and reproductive methods. Algae are simple, thalloid organisms, while bryophytes lack a true vascular system and reproduce via spores. Pteridophytes are vascular but seedless, with spores as their reproductive structure. Gymnosperms are vascular seed-bearing plants with naked seeds, and angiosperms are vascular, seed-bearing plants with seeds enclosed in fruits and flowers.