Key PointsState Street SPDR S&P Aerospace & Defense ETF offers a slightly lower expense ratio of 0.35% compared to the 0.38% charged by iShares U.S. Aerospace & Defense ETF.iShares U.S. Aerospace & Defense ETF provides a higher dividend yield, but State Street SPDR S&P Aerospace & Defense ETF has delivered stronger total returns over the past 12 months.The iShares U.S. Aerospace & Defense ETF is more concentrated in its top holdings, while State…