Spreads can be higher on MT4 because MT4 is so backwards we have to group the instruments into groups and add the same spread to all in the group.
On MT5 the spreads are not grouped we can add mark ups to individual instruments rather than grouped so they are usually lower in MT5.
The reason you may see gaps on MT5 is because you need to use the true bid ask indicator to show the true price. This is free to download in the downloads section in your client portal. Because MT5 instruments are not grouped, the bid ask line on the chart only shows the raw spread. If you use the indicator it shows the actual spread including mark up.
On MT4 it shows the spread including mark up.
Its just a weird Metatrader thing which is unfortunately out of our control.