Nondescrimination requirements for leased employees

[katieinny]

An employer is leasing some employees who are covered by the leasing organization's plan. The employer's plan has a slightly better contribution formula than the leasing organization's plan, so the employer will give the leased employees the difference.

Does the employer also have to be concerned about meeting a benefits, rights and features test for the leased employees? In other words, does he have to compare his plan to the leasing organization's plan to make sure there's no discrimination for provisions other than the contribution formula? For example, distribution options?