The difference between Orb and Sphere

Orb as a noun:

A spherical body; a globe; especially, one of the celestial spheres; a sun, planet, or star

Orb as a noun:

One of the azure transparent spheres conceived by the ancients to be enclosed one within another, and to carry the heavenly bodies in their revolutions

Orb as a noun:

A circle; especially, a circle, or nearly circular orbit, described by the revolution of a heavenly body; an orbit

Orb as a noun (rare):

A period of time marked off by the revolution of a heavenly body.

Orb as a noun (poetic):

The eye, as luminous and spherical

Orb as a noun (poetic):

A revolving circular body; a wheel

Orb as a noun (rare):

A sphere of action.

Orb as a noun:

A globus cruciger; a ceremonial sphere used to represent royal power

Orb as a noun:

A translucent sphere appearing in flash photography (Orb (optics))

Orb as a noun (military):

A body of soldiers drawn up in a circle, as for defence, especially infantry to repel cavalry.

Orb as a verb (poetic, transitive):

To form into an orb or circle.

Orb as a verb (poetic, intransitive):

To become round like an orb.

Orb as a verb (poetic, transitive):

To encircle; to surround; to enclose.

Orb as a noun (architecture):

A blank window or panel.

Sphere as a noun (mathematics):

A regular three-dimensional object in which every cross-section is a circle; the figure described by the revolution of a circle about its diameter .

Sphere as a noun:

A spherical physical object; a globe or ball.

Sphere as a noun (astronomy, now, _, rare):

The apparent outer limit of space; the edge of the heavens, imagined as a hollow globe within which celestial bodies appear to be embedded.

Sphere as a noun (historical, astronomy, mythology):

Any of the concentric hollow transparent globes formerly believed to rotate around the Earth, and which carried the heavenly bodies; there were originally believed to be eight, and later nine and ten; friction between them was thought to cause a harmonious sound (the music of the spheres).

Sphere as a noun (mythology):

An area of activity for a planet; or by extension, an area of influence for a god, hero etc.

Sphere as a noun (figuratively):

The region in which something or someone is active; one's province, domain.

Sphere as a noun (geometry):

The set of all points in three-dimensional Euclidean space (or n-dimensional space, in topology) that are a fixed distance from a fixed point .

Sphere as a noun (logic):

The extension of a general conception, or the totality of the individuals or species to which it may be applied.

Sphere as a verb (transitive):

To place in a sphere, or among the spheres; to ensphere.

Sphere as a verb (transitive):

To make round or spherical; to perfect.