Bond Enthalpy:
Bond enthalpy, also known as bond energy, is the energy required to break a covalent bond in a gaseous molecule, or the energy released when a bond is formed. It is a measure of the strength of a chemical bond. Bond enthalpy is expressed in units of kilojoules per mole (kJ/mol).

Lattice Enthalpy:
Lattice enthalpy, also known as lattice energy, is the energy released when one mole of an ionic crystal lattice is formed from its gaseous ions. It represents the strength of the ionic bond between the ions in the lattice. Lattice enthalpy is also expressed in units of kilojoules per mole (kJ/mol).

Differences:
1. Definition: The main difference between bond enthalpy and lattice enthalpy lies in their definitions. Bond enthalpy refers to the energy required to break or form a covalent bond, whereas lattice enthalpy refers to the energy released when ionic compounds are formed.

2. Types of Bonds: Bond enthalpy applies to covalent bonds, which involve the sharing of electrons between atoms. On the other hand, lattice enthalpy applies to ionic compounds, where ions of opposite charges are held together by electrostatic forces.

3. Formation and Breaking: Bond enthalpy involves breaking or forming a single bond between two atoms. It measures the energy change associated with this process. Lattice enthalpy, on the other hand, involves the formation of an entire crystal lattice from gaseous ions. It measures the energy released when this process occurs.

4. Strength of Bonds: Bond enthalpy provides information about the strength of individual covalent bonds. It can vary depending on the atoms involved and the specific molecular structure. Lattice enthalpy, on the other hand, represents the overall strength of the ionic bond in a crystal lattice. It is influenced by factors such as the charges and sizes of the ions.

5. Significance: Bond enthalpy is important in understanding the reactivity and stability of covalent compounds. It helps to predict the energy changes in chemical reactions involving the breaking or forming of bonds. Lattice enthalpy is crucial in determining the stability and properties of ionic compounds. It affects properties such as melting point, solubility, and conductivity.

In summary, bond enthalpy and lattice enthalpy are both measures of the energy associated with chemical bonds but apply to different types of bonds. Bond enthalpy refers to covalent bonds, while lattice enthalpy refers to ionic compounds. Understanding these concepts is essential in studying the energetics and behavior of chemical compounds.