Broad synonym,synonyms of broad

Similarities: Both "broad" and "wide" are used to describe something that has a large extent from side to side. They can be used interchangeably in many cases when referring to physical dimensions. For example, we can say "a broad/wide road" or "a broad/wide river". They both give the sense of something having a significant lateral span.
Differences: "Wide" is more commonly used when specifically emphasizing the measurement or extent of something from one side to the other in a physical sense. It is often used in more technical or precise descriptions of width. "Broad" can have a more general or figurative sense in addition to the physical one. For instance, "broad shoulders" gives a more general impression of the shoulders being large and wide, while "wide shoulders" might focus more on the actual width measurement.

Similarities: "Vast" and "broad" both convey a sense of largeness and expansiveness. When describing something like a "vast/broad plain" or a "vast/broad ocean", they both suggest that the area is extremely large and extensive.
Differences: "Vast" emphasizes an almost overwhelming sense of immensity and great extent, often implying that the area or space is so large that it is difficult to comprehend or measure. It is more often used to describe very large and open spaces or quantities. "Broad" can be used for a somewhat smaller scale of width or extent and also has other meanings like being comprehensive or general, which "vast" doesn't have as strongly. For example, we might say "broad knowledge" but not "vast knowledge" in the same sense.

Similarities: "Extensive" and "broad" share the idea of covering a large area or having a wide range. We can say "extensive/broad research" to indicate that the research has covered a lot of ground or a wide range of topics. They both imply a significant degree of comprehensiveness.
Differences: "Extensive" is often used to describe something that has a large scope or range in a more abstract or non-physical sense, like extensive experience or extensive damage. It focuses on the idea of covering a lot of ground or having a large quantity or degree. "Broad" can be used in both physical and abstract senses, but "extensive" is less likely to be used to describe the physical width of an object in the same way as "broad". For example, we would say "a broad street" rather than "an extensive street" when referring to the width.

Similarities: In an abstract sense, "comprehensive" and "broad" can both mean covering a wide range of things. When we talk about a "comprehensive/broad understanding" of a subject, it means that the understanding includes many aspects and is not limited or narrow.
Differences: "Comprehensive" emphasizes the idea of being complete and including all relevant aspects or details. It implies a thoroughness and inclusiveness. "Broad" is a bit more general and may not carry the same connotation of being completely thorough and detailed. A "broad overview" gives a general sense of something, while a "comprehensive overview" would imply that it includes all the important details and aspects.

Similarities: "General" and "broad" can both have the meaning of being not specific or detailed but covering a wide range or having a wide application. For example, a "general/broad principle" is one that applies to many situations and is not too specific.
Differences: "General" often implies a lack of specificity or detail and is more about being applicable in a wide range of cases or having a common or overall nature. "Broad" can have a more physical or spatial connotation in addition to the abstract one. "General" is more about the nature of being common or widespread in a conceptual sense, while "broad" can refer to physical width or a more tangible sense of expansiveness as well as the abstract sense of being wide-ranging.