I think the critical difference between the two systems is that the US allows joint sponsorship and the UK doesn't. What that means is that if you wanted to move back to the UK in the future, without Citizenship, your husband would need to move ahead of you.
UKC can be obtained only after ILR in addition to minimum resistance requirements, passing the life in the UK test and being of 'good character'.
Starting out on a spousal visa, this lasts for 2.5 years at which you then apply for Further Leave to Remain (FLR). FLR lasts for another 2.5 years at which you can then apply for ILR. Only after ILR has been granted can you apply for citizenship. There are financial sponsorship requirements on your husband for spousal visa, FLR and ILR. Joint sponsorship in the UK is not allowed. For the visa and FLR, you must also pay the NHS surcharge.
Given that there are effectively four points of application until citizenship is approved, there are 4 opportunities for the authorities to make the next step more expensive or more difficult. Since this particular process was introduced in 2012, they have done this a number of times. Hence my recommendation to get UKC over and done with if you're already here. Hope this helps!
UKC married to USC 2012.
USC is on FLR(M) - 1 year to go to ILR
Sent from my iPhone using Tapatalk