What's the core difference between the electric and magnetic forces? I require only a simple answer. One sentence is enough... (It's for high school physics)
 A: For the purposes of high school physics it is reasonable to say that electric fields start and stop on charges but magnetic fields always run in loops.

This fails to be rigorous in at least two ways:


*

*Relative velocity mixes the two types of fields in a manner governed by the Lorentz transform, so the truth is like wsc says.

*It is an open question if there exist any magnetic monopoles, but theoretical prejudice favors their existence for reasons of beauty.

A: Consult this document by Hans de Vries:
The simplest, and the full derivation of Magnetism as a Relativistic side efect of ElectroStatics
He uses only Electrostactic field and the non-simultaneity to derive the Magnetic Field.
It appears that the Magnetic field is a side effect of movement of charges in the electric field.
If we pretend that the magnetic field exists beyond a mere artifact then the following question must be answered:
How can the particles communicate information about its position and velocity so that, in the past, they can adjust the source of the electromagnetic energy?
(*) Hans de Vries has a very interesting online book (not yet finished) in his site.
added:
Magnetic forces are induced by the motion and, much like Coriolis force, is not a real force.  ...
wikipedia ..the Coriolis effect is an apparent deflection of moving objects when they are viewed from a rotating reference frame. (a moving frame induces forces, there is no need to be a rotating one)
ps: it is frustating to be down voted without a comment  :(  it´s an injustice......yes it is - Calimero.
A: Electric forces are created by and act on, both moving and stationary charges; while magnetic forces are created by and act on only moving charges.
A: Electric monopoles exist. Magnetic monopoles don't* exist.
This is the reason that Maxwell's laws governing electricity and magnetism aren't symmetric. Maxwell's laws say that $\nabla \cdot B = 0$ and $\nabla \cdot E = 4\pi\rho_{e}$, but if magnetic monopoles existed this would be $\nabla \cdot B = 4\pi\rho_{m}$ and $\nabla \cdot E = 4\pi\rho_{e}$. A similar asymmetry in induction would be corrected.
The experimental lack of evidence for magnetic monopoles can then be taken as the main reason we distinguish between the two forces.
*(Probably.)
A: Not to be slick, but starting with Hans Christian Ørsted, then on through James Clerk Maxwell and Albert Einstein we time and again reinforce that there is none -- they are heads and tails of the same coin.
A: Unlike electric fields, magnetic fields do no work on charges.
A: Magnetic forces are always normal to the direction of the velocity of the charge it acts upon, whereas electric force are independent of the direction the charge moves in.
A: Electric forces act between charged bodies (charges), magnetic forces act between magnetized bodies (magnets). The latter can be said differently: magnetic forces act between currents of neutralized charges.
A: Electric fields are divergent, magnetic fields are convergent.
Why the downvote?  Anyone?
