The first, the difference is between an Index fund vs Exchange Traded Fund. The former is bought from the fund manager whilst the latter is traded like a stock on the exchanges and you buy it through at broker at the market price.
For the second the difference isn't very clear to me, maybe the first is structured as an irish UCITS whilst the second is a UK based passive fund?
The third, the difference is between a unit trust and an ETF. A unit trust holds a portfolio of assets and you buy a share of that portfolio.