What are the differences between intracellular and intercellular signaling?

Intracellular signaling 

Intracellular signaling refers to cell communication that takes place in the cytoplasm within the cell in response to various intracellular and extracellular stimuli. This form of cellular communication uses secondary messengers such as cyclic AMP, calcium ion, inositol triphosphate, and diacylglycerol. Intracellular signaling is responsible for controlling all the functions that take place in the cell including cell division activity, morphology, intermediary metabolism, and the transcription program.  

Intercellular signaling

Intercellular signaling refers to the communication that takes place between cells in the extracellular matrix. In animals, intercellular signaling between neighboring cells occurs via gap junctions. In plants, intercellular signaling between neighboring cells occurs via plasmodesmata. Intercellular signaling is critical for the differentiation and development of an organism and processing sensory information.