What is the difference between 'Electrospray Ionisation' and 'Electron Impact' during the ionisation stage in a mass spectrometer?

Mass Spectrometry is often used by scientists to determine all the isotopes present in a sample (using their isotopic masses) and thus identify the element. The first stage is called the 'ionisation stage' and interestingly there are 2 methods undertaken to ionise a sample. Electrospray ionisation is where a sample is dissolved in a volatile, polar solvent. It is then injected through a fine hypodermic needle creating a fine mist or aerosol. A high voltage is now applied to the tip of the needle, causing the sample molecule, M, to gain a proton and form MH⁺. The solvent then evaporates away, leaving the MH⁺ ions, which are then attracted and accelerated towards the negative plate. In contrast, 'Electron Impact' is where a vaporised sample is injected at low pressures, and high energy electrons are fired towards the sample. This removes/knocks off one outer electron forming positive ions. Electron impact is used for elements and substances with low formula masses as it would otherwise cause larger organic molecules to fragment.