In alpha decay, an alpha particle, which is a helium nucleus consisting of two protons and two neutrons, is emitted from the parent nucleus. This results in the formation of a daughter nucleus with two less protons and two less neutrons than the parent nucleus.
For example, when uranium-238 undergoes alpha decay, it emits an alpha particle and transforms into thorium-234:
$$^{238}U \rightarrow ^{4}He + ^{234}Th$$
In beta decay, a neutron in the parent nucleus is converted into a proton, an electron (or positron in case of beta+ decay) and an antineutrino (or neutrino in case of beta+ decay). This results in the formation of a daughter nucleus with the same number of protons but an additional electron (or one less electron in beta+ decay) compared to the parent nucleus.
For example, when carbon-14 undergoes beta decay, it emits an electron (or positron) and an antineutrino and transforms into nitrogen-14:
$$^{14}C \rightarrow ^{14}N + e^- (\text{or} e^+) + \bar{\nu} (\text{or} \nu)$$
Therefore, in beta decay, the parent element and daughter can be different isotopes of the same element, or they can be different elements altogether.
