The two atomic bonds (ionic and covalent bonds) differ in structure and properties.
A covalent bond occurs between atoms of the same element which have similar electro negativities or between two nonmetal atoms that have same electronegativity. The bond is formed when electrons in the outer orbitals are shared between the atoms. This results into the formation of a molecule. Compounds formed through covalent bonding are called covalent compounds. Covalent compounds dissolve in water but do not dissociate into ions.
On the other hand, an ionic bond is formed between a metal and a nonmetal atom. Ionic bonds occur where difference in electronegativity of the atoms involved is large. This occurs in a manner that the metal atom donates (an) electron(s) from the outermost orbit to the nonmetal atom. The metal atom is thus referred to as donor atom while the nonmetal atom is referred to as the receptor atom. This results in the formation of charged particles called ions. The metal atom forms a positively charged ion and the nonmetal forms a negatively charged ion. The positive ion is called a cation and the negatively charged ion is called an anion. An example of an ionic bond is one that occurs between sodium Na and Chlorine Cl. When the two react, they form sodium chloride NaCl which is an ionic compound. Ionic compounds dissociate into ions when they dissolve in water.
The atoms before they form the bonds have an unstable electron configuration which is the reason why bonding occurs so as to have a stable electron configuration. Also in both cases, more than one electron can be involved in the formation of the bonds. In formation of ionic bonds, more than one electron can be donated for the formation of the bond and in the formation of covalent bonds, more than one electron can be shared.