Difference between 'POST' and $.post

in this case the the token was properly posted

$.post(serviceURL, {Ids: ids,actionId: action.Id, __RequestVerificationToken: token },
             function (data) {


while this way

$.ajax(
      {
            url: serviceURL,
             type: 'POST',
              contentType: "application/json; charset=utf-8",
            data: {
                    Ids: ids,
                   actionId: action.Id,
               __RequestVerificationToken: token

it wasn't. No idea why.