You might mean the difference between the traditional, built in way using \newcommand or \def vs. keys such as pgf keys. At the surface they are very different, internally keys use \def (and its variants like \edef) in some clever ways.
– Feb 07 '20 at 07:34
2
please complete the post to contain an actual question. {} and = are different and there are very few places where you have a choice over which to use, so I can not guess what question you are asking here?
– David CarlisleFeb 07 '20 at 07:56
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Taking into account that OP's author ask about LaTeX commands, it seems to me that he means commands for dimensions setting and difference between \mydimen = 1pt and \setlength{\mydimen}{1pt}. If that's so, there is no fundamental difference between this two notation. But more clarification needs.
– Mr. SandmanFeb 07 '20 at 08:13
\newcommandor\defvs. keys such as pgf keys. At the surface they are very different, internally keys use\def(and its variants like\edef) in some clever ways. – Feb 07 '20 at 07:34{}and=are different and there are very few places where you have a choice over which to use, so I can not guess what question you are asking here? – David Carlisle Feb 07 '20 at 07:56\mydimen = 1ptand\setlength{\mydimen}{1pt}. If that's so, there is no fundamental difference between this two notation. But more clarification needs. – Mr. Sandman Feb 07 '20 at 08:13