From a feature standpoint, 1.7.0 release of these two instrumentation libraries don't have any additional changes on top of the respective 1.6.0 version packages. The major difference in 1.7.0 is that it depends on 1.7.0 version of OpenTelemetry.Api.ProviderBuilderExtensions which brings in >=8.0.0 version of System.Diagnostics.DiagnosticSource.
If you're interested in knowing all of the changes that went into 1.6.0 release, please go through the Release notes of all the previous pre-release versions for 1.6.0 for these two packages.