Table 1.

Differences between cross-device FL and cross-silo FL

Aspects	Cross-silo FL	Cross-device FL
Setting	Clients are usually large institutions. Each client reserves a large number of training samples and has sufficient training resources.	Clients are usually portable devices and lack training resources.
Data availability	Clients are almost always available	Only some clients can be used for training at certain time periods.
Federation scale	The number of clients is usually less than 100.	The amount of the client is about ${10}^{10}$.
Primary bottleneck	Communication and computation	Communication
Addressability	Each client is assigned an identity.	Customers usually cannot be directly indexed.
Client reliability	Usually few errors.	High error rate.
Data partition axis	Horizontal or vertical.	Horizontal.