The reason why casein is considered to be a slower digesting protein is that it curdles inside the stomach, making it difficult to digest, so its amino acids are released slowly. It's reasonable to assume that this effect is unique to casein, and that all other proteins are "fast digesting".
It's also pretty questionable whether this slow-digesting property of casein is actually beneficial, as not only is casein inferior at stimulating muscle growth compared to whey1, but the body also experiences a refractory period in response to elevated blood amino acids, where muscle protein synthesis stops after a while and does not respond to continued elevated blood amino acids2, suggesting that slow-digesting proteins are in general not useful.
That said, this does not appear to have ever actually been tested, i.e. there is no study I could find which fed participants protein before bed, divided into whey and casein groups, and measured total overnight muscle protein synthesis. So any claims about which is better for consumption prior to bed should be regarded as merely speculative.
- Tang, J. E., Moore, D. R., Kujbida, G. W., Tarnopolsky, M. A., & Phillips, S. M. (2009). Ingestion of whey hydrolysate, casein, or soy protein isolate: effects on mixed muscle protein synthesis at rest and following resistance exercise in young men. Journal of Applied Physiology, 107(3), 987–992. https://doi.org/10.1152/japplphysiol.00076.2009
- Mitchell, W. K., Phillips, B. E., Hill, I., Greenhaff, P., Lund, J. N., Williams, J. P., Rankin, D., Wilkinson, D. J., Smith, K., & Atherton, P. J. (2017). Human skeletal muscle is refractory to the anabolic effects of leucine during the postprandial muscle-full period in older men. Clinical Science, 131(21), 2643–2653. https://doi.org/10.1042/cs20171230