Final answer:
Beta decay and alpha decay differ in that beta decay involves the emission of electrons or positrons, altering the atomic number, whereas alpha decay involves the release of alpha particles (helium ions) without changing the atomic number.
Step-by-step explanation:
The common characteristic among the different types of beta decay (β-decay) that sets them apart from alpha decay (α-decay) is the emission of electrons or positrons (antielectrons). Unlike alpha decay which involves the expulsion of helium ions (alpha particles), beta decay involves the transformation of nucleons within the nucleus. Specifically, in beta minus (β-) decay, a neutron is converted into a proton and an electron, with the electron being emitted. In beta plus (β+) decay, also known as positron emission, a proton is transformed into a neutron and a positron, with the positron being emitted. Both of these processes alter the atomic number of the element, with beta minus decay increasing it by one and beta plus decay decreasing it by one.