I want to know Lazarus version rules. ex)between 1.4 1.2 or 1.0 1.2 ...
Those are so called major version changes. It means they include all new development from the trunk branch. Thus they require a stabilization period and release candidates before the actual release.
Minor versions like 1.4.2 and 1.4.4 are bug fix releases. Only selected fixes from trunk are backported for them.
When does the first number change? It is a more arbitrary decision. For example we don't know yet if the next major version will be 1.6 or 2.0. Changing the first number typically involves a big change that may break compatibility with earlier versions.