Creating a grid between two vector3s?

I can't really seem to get anywhere with this, but I want to make a grid through two vector3s.

This is what I have.

local function createGrid(start, goal)
    local rows = 5
    local cols = 5
    local tileSize = 1

    for i = 1, rows, 1 do
        for j = 1, cols, 1 do
            local part = Instance.new("Part")
            part.Anchored = true
            part.Parent = workspace.Parts
            part.Name = i.." : "..j
            part.Size = Vector3.new(tileSize, 0.25, tileSize)
            part.Position = Vector3.new(
                i * part.Size.X,
                1,
                j * part.Size.Z
            )
        end
    end


end

createGrid(workspace.Start.Position, workspace.End.Position)

Any help is appreciated.