they are two different products.......sort of. the Essentials for Life is basically an herb based meal replacer to be put in the same class as critical care. my chins prefer the EFL to the CC.
lifeline while also herb based is more herb intensive and can be used as a meal replacer but would not be cost effective. i use lifeline for sick chins in addition to the EFL or for chins that need a boost, have gas, etc.... i have a few that when it is mixed thick will eat it right off the spoon. others turn their nose to it.
for my dental chin, i put the lifeline in the coffee grinder and mix it thinner to fit in the tiny 1 cc syringe and mix it with meds or even gas drops. when crushed it doesnt clog the syringe.
personally, i keep both EFL & lifeline as a staple in my fridge for my chins.