Different uses of tag in Document index

[schalkneethling]

I am curious what is the difference or benefit of creating an index is between the following.

Example Data

const data = [
  {
    id: 1,
    title: "Mozilla Firefox",
    engine: "Gecko",
    tag: ["servo", "rust", "spider monkey"],
  },
  {
    id: 2,
    title: "Google Chrome",
    engine: "Chromium",
    tag: ["blink", "v8"],
  },
  {
    id: 3,
    title: "Microsoft Edge",
    engine: "Chromium",
    tag: ["blink", "chakra"],
  },
  {
    id: 4,
    title: "Apple Safari",
    engine: "Webkit",
    tag: ["JavaScriptCore", "SquirrelFish", "nitro"],
  },
];

Index example 1

export const indexDataCustomTokenizer = (tokenizerType = "strict") => {
  const index = new Document({
    document: { index: ["engine", "tag", "title"] },
    tokenize: tokenizerType,
  });
  data.forEach((item) => index.add(item));

  return index;
};

Index example 2

export const indexDataCustomTokenizer = (tokenizerType = "strict") => {
  const index = new Document({
    document: { index: ["engine", "title"], tag: "tag" },
    tokenize: tokenizerType,
  });
  data.forEach((item) => index.add(item));

  return index;
};

For one thing, using the second index will not yield any results if the query uses for example, "spider" while the first index will return the relevant result. Looking forward to learning more.