Definitions
Gymnosperm:
The Gymnosperms are the cone-bearing plants--pines, junipers, spruces,
firs, hemlocks, bald cypresses, eastern white cedar, Atlantic white
cedar, and their relatives. The name means "naked seeded"
which means that the ovule (the egg cell) is not covered by an organ
(the ovary in floweirng plants) but is born on the scale of a structure
called a "cone". When the cone and seeds mature, the seeds
are often exposed to the environment (however, the cone scales can
be fleshy and can tightly cover the seeds, as in the junipers).
Angiosperm:
The Angiosperms are the true flowering plants. The name means "covered
seeded" which means that the ovule (the egg cell) is covered
by an organ called the ovary. As the egg develops to a seed, the ovary
often develops as well--into the fruiting structure. The flowering
plants are more recent evolutionarily than the gymnosperms and more
diverse and variable.