SObjects have get and set methods which you can use to set/get the values of fields. To implement this you could use a string map to work out what goes where:

Map<String, String> AFieldToBField = new Map<String, String>
{
  'SVCMP__xyz__c' => 'xyz__ c',
  'SVCMP__abc__c' => 'abc__ c'
};

for(String key : AFieldToBField.KeySet())
{
    objA.put(key, objB.get(key));
}

Obviously this is only going to work if the fields are of the same types on each object, otherwise you're going to need to deal with conversion as well.

SObjects have get and set methods which you can use to set/get the values of fields.

If the fields are of the same type and the only difference is that objA has a prefix in the field API names, i.e. SVCM__ then you can just loop over the field names in the objB list (which you say you have) and then add the prefix when getting fields from objA:

for(String field : objBFields)
{
  objBRecord.set(field, objARecord.get('SVCM__' + field));
}

If the field names have other variances and you need a full map then you could implement this you could use a string map to work out what goes where:

Map<String, String> AFieldToBField = new Map<String, String>
{
  'SVCMP__xyz__c' => 'xyz__ c',
  'SVCMP__abc__c' => 'abc__ c'
};

for(String key : AFieldToBField.KeySet())
{
    objA.put(key, objB.get(key));
}

Obviously this is only going to work if the fields are of the same types on each object, otherwise you're going to need to deal with conversion as well.