Key Difference:  Radioactive Decay is the process by which an atomic nucleus emits elementary particles or fragments. This breakdown of the atomic nucleus results in release of energy as well as matter from the nucleus. Generally, transmutation refers to the act of change from one form to another. In context to nuclear transmutation, it may refer to radioactive process, nuclear fission or nuclear fusion where the form of element is changed from one to another.

Radioactive Decay is the process by which an atomic nucleus emits elementary particles or fragments. This breakdown of the atomic nucleus results in release of energy as well as matter from the nucleus. Generally, transmutation refers to the act of change from one form to another. In context to nuclear transmutation, it may refer to radioactive, nuclear fission or nuclear fusion where the form of element is changed from one to another.

Whenever the decay happens, the parent element’s nucleus changes to form a daughter element, which is different from the parent nucleus. It happens due the fact that number of protons change in the process of radioactive decay. These nuclei are referred to as radioactive which means that they are unstable and therefore go through the process of decay. Decays take place until a stable nucleus is formed.

Principles of conservation are applied during radioactive decay. These principles include conservation of energy, momentum, charge and nucleon number.

Transmutation generally refers to the act of change from one form to another. Transmutation occurs in the process of radioactive decay where it is achieved by both natural and artificial ways. Apart from occurring spontaneously by radioactive decay, transmutation may also be induced by a nuclear reaction like neutron capture. Nuclear transmutation can also be found in nuclear fission and nuclear fusion. In nuclear fission heavy elements split into lighter elements. In nuclear fusion lighter elements combine to form heavier one.

The term transmutation is used in many contexts. In biology, it refers to the process of transformation of one species into another. In Alchemy, it is the supposed conversion of base metals into some precious metals like gold and silver.

Therefore, the radioactive decay refers to the change in nucleus which takes place when an unstable nucleus tries to reach a stable form. In this process, energy and matter are released from nucleus. On the other hand, transmutation refers to the change in nucleus, especially referring to the change in form from one to another.

Comparison between Radioactive Decay and Transmutation:

	Radioactive Decay	Transmutation
Definition	Radioactive Decay is the process by which an atomic nucleus emits elementary particles or fragments. It is a spontaneous transformation of one element into another.	Generally, transmutation refers to the act of change from one form to another. In context to nuclear transmutation, it may refer to radioactive, nuclear fission or nuclear fusion where the form of element is changed from one to another.
Types	Alpha decay – the mass number of parent element decreases by four and the atomic number is decreased by two Beta decay – occurs in two forms. Either nucleus’s neutrons are transformed into a proton, an electron and an antineutrino or a proton is changed into a neutron, a positron and a neutrino. Gamma decay – atomic nucleus gets rid of the energy after undergoing alpha or beta decay by emitting gamma rays	Nuclear Transmutations can be broadly divided into two types – Nuclear reaction involving an outside particle to reach with a nucleus. Radioactive decay which do not require an outside particle.
Example
Conservation laws	These principles include conservation of energy, momentum, charge and nucleon number.	Two fundamental laws are always followed – mass number and electrical charge is conserved

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