With the DX CLI you can't deploy certain individual files - ex. aura and lightning components. You have to use syntax like
sfdx force:source:deploy -m AuraDefinitionBundle:<aura bundle name>,ApexClass:<some class name> and so on.
Is there any definitive list of all possible types of 'prefixes' like
AuraDefinitionBundle: in SFDC docs? I've not yet come across one on https://developer.salesforce.com/docs/atlas.en-us.sfdx_cli_reference.meta/sfdx_cli_reference/cli_reference.htm